/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.telecom;

import com.android.internal.os.SomeArgs;
import com.android.internal.telecom.IVideoCallback;
import com.android.internal.telecom.IVideoProvider;

import android.annotation.NonNull;
import android.annotation.Nullable;
import android.annotation.SystemApi;
import android.app.Notification;
import android.bluetooth.BluetoothDevice;
import android.content.Intent;
import android.hardware.camera2.CameraManager;
import android.net.Uri;
import android.os.Binder;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
import android.os.Looper;
import android.os.Message;
import android.os.ParcelFileDescriptor;
import android.os.RemoteException;
import android.os.SystemClock;
import android.util.ArraySet;
import android.view.Surface;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.nio.channels.Channels;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

Represents a phone call or connection to a remote endpoint that carries voice and/or video
traffic.
 Implementations create a custom subclass of Connection and return it to the framework as the return value of ConnectionService.onCreateIncomingConnection(PhoneAccountHandle, ConnectionRequest) or ConnectionService.onCreateOutgoingConnection(PhoneAccountHandle, ConnectionRequest). Implementations are then responsible for updating the state of the Connection, and must call destroy() to signal to the framework that the Connection is no longer used and associated resources may be recovered. 
 Subclasses of Connection override the on* methods to provide the the ConnectionService's implementation of calling functionality. The on* methods are called by Telecom to inform an instance of a Connection of actions specific to that Connection instance. 
 Basic call support requires overriding the following methods: onAnswer(), onDisconnect(), onReject(), onAbort() 
 Where a Connection has CAPABILITY_SUPPORT_HOLD, the onHold() and onUnhold() methods should be overridden to provide hold support for the Connection. 
 Where a Connection supports a variation of video calling (e.g. the CAPABILITY_SUPPORTS_VT_* capability bits), onAnswer(int) should be overridden to support answering a call as a video call. 
 Where a Connection has PROPERTY_IS_EXTERNAL_CALL and CAPABILITY_CAN_PULL_CALL, onPullExternalCall() should be overridden to provide support for pulling the external call. 
 Where a Connection supports conference calling onSeparate() should be overridden. 
 There are a number of other on* methods which a Connection can choose to implement, depending on whether it is concerned with the associated calls from Telecom. If, for example, call events from a InCallService are handled, onCallEvent(String, Bundle) should be overridden. Another example is onExtrasChanged(Bundle), which should be overridden if the Connection wishes to make use of extra information provided via the Call.putExtras(Bundle) and Call.removeExtras(String...) methods. /**
 * Represents a phone call or connection to a remote endpoint that carries voice and/or video
 * traffic.
 * <p>
 * Implementations create a custom subclass of {@code Connection} and return it to the framework
 * as the return value of
 * {@link ConnectionService#onCreateIncomingConnection(PhoneAccountHandle, ConnectionRequest)}
 * or
 * {@link ConnectionService#onCreateOutgoingConnection(PhoneAccountHandle, ConnectionRequest)}.
 * Implementations are then responsible for updating the state of the {@code Connection}, and
 * must call {@link #destroy()} to signal to the framework that the {@code Connection} is no
 * longer used and associated resources may be recovered.
 * <p>
 * Subclasses of {@code Connection} override the {@code on*} methods to provide the the
 * {@link ConnectionService}'s implementation of calling functionality.  The {@code on*} methods are
 * called by Telecom to inform an instance of a {@code Connection} of actions specific to that
 * {@code Connection} instance.
 * <p>
 * Basic call support requires overriding the following methods: {@link #onAnswer()},
 * {@link #onDisconnect()}, {@link #onReject()}, {@link #onAbort()}
 * <p>
 * Where a {@code Connection} has {@link #CAPABILITY_SUPPORT_HOLD}, the {@link #onHold()} and
 * {@link #onUnhold()} methods should be overridden to provide hold support for the
 * {@code Connection}.
 * <p>
 * Where a {@code Connection} supports a variation of video calling (e.g. the
 * {@code CAPABILITY_SUPPORTS_VT_*} capability bits), {@link #onAnswer(int)} should be overridden
 * to support answering a call as a video call.
 * <p>
 * Where a {@code Connection} has {@link #PROPERTY_IS_EXTERNAL_CALL} and
 * {@link #CAPABILITY_CAN_PULL_CALL}, {@link #onPullExternalCall()} should be overridden to provide
 * support for pulling the external call.
 * <p>
 * Where a {@code Connection} supports conference calling {@link #onSeparate()} should be
 * overridden.
 * <p>
 * There are a number of other {@code on*} methods which a {@code Connection} can choose to
 * implement, depending on whether it is concerned with the associated calls from Telecom.  If,
 * for example, call events from a {@link InCallService} are handled,
 * {@link #onCallEvent(String, Bundle)} should be overridden.  Another example is
 * {@link #onExtrasChanged(Bundle)}, which should be overridden if the {@code Connection} wishes to
 * make use of extra information provided via the {@link Call#putExtras(Bundle)} and
 * {@link Call#removeExtras(String...)} methods.
 */
public abstract class Connection extends Conferenceable {

    
The connection is initializing. This is generally the first state for a Connection returned by a ConnectionService. /**
     * The connection is initializing. This is generally the first state for a {@code Connection}
     * returned by a {@link ConnectionService}.
     */
    public static final int STATE_INITIALIZING = 0;

    
The connection is new and not connected.
/**
     * The connection is new and not connected.
     */
    public static final int STATE_NEW = 1;

    
An incoming connection is in the ringing state. During this state, the user's ringer or
vibration feature will be activated.
/**
     * An incoming connection is in the ringing state. During this state, the user's ringer or
     * vibration feature will be activated.
     */
    public static final int STATE_RINGING = 2;

    
An outgoing connection is in the dialing state. In this state the other party has not yet
answered the call and the user traditionally hears a ringback tone.
/**
     * An outgoing connection is in the dialing state. In this state the other party has not yet
     * answered the call and the user traditionally hears a ringback tone.
     */
    public static final int STATE_DIALING = 3;

    
A connection is active. Both parties are connected to the call and can actively communicate.
/**
     * A connection is active. Both parties are connected to the call and can actively communicate.
     */
    public static final int STATE_ACTIVE = 4;

    
A connection is on hold.
/**
     * A connection is on hold.
     */
    public static final int STATE_HOLDING = 5;

    
A connection has been disconnected. This is the final state once the user has been
disconnected from a call either locally, remotely or by an error in the service.
/**
     * A connection has been disconnected. This is the final state once the user has been
     * disconnected from a call either locally, remotely or by an error in the service.
     */
    public static final int STATE_DISCONNECTED = 6;

    
The state of an external connection which is in the process of being pulled from a remote
device to the local device.
 A connection can only be in this state if the PROPERTY_IS_EXTERNAL_CALL property and CAPABILITY_CAN_PULL_CALL capability bits are set on the connection. /**
     * The state of an external connection which is in the process of being pulled from a remote
     * device to the local device.
     * <p>
     * A connection can only be in this state if the {@link #PROPERTY_IS_EXTERNAL_CALL} property and
     * {@link #CAPABILITY_CAN_PULL_CALL} capability bits are set on the connection.
     */
    public static final int STATE_PULLING_CALL = 7;

    
Connection can currently be put on hold or unheld. This is distinct from CAPABILITY_SUPPORT_HOLD in that although a connection may support 'hold' most times, it does not at the moment support the function. This can be true while the call is in the state STATE_DIALING, for example. During this condition, an in-call UI may display a disabled 'hold' button. /**
     * Connection can currently be put on hold or unheld. This is distinct from
     * {@link #CAPABILITY_SUPPORT_HOLD} in that although a connection may support 'hold' most times,
     * it does not at the moment support the function. This can be true while the call is in the
     * state {@link #STATE_DIALING}, for example. During this condition, an in-call UI may
     * display a disabled 'hold' button.
     */
    public static final int CAPABILITY_HOLD = 0x00000001;

    
Connection supports the hold feature. /** Connection supports the hold feature. */
    public static final int CAPABILITY_SUPPORT_HOLD = 0x00000002;

    
Connections within a conference can be merged. A ConnectionService has the option to add a Conference before the child Connections are merged. This is how CDMA-based Connections are implemented. For these unmerged Conferences, this capability allows a merge button to be shown while the conference is in the foreground of the in-call UI. 
 This is only intended for use by a Conference. /**
     * Connections within a conference can be merged. A {@link ConnectionService} has the option to
     * add a {@link Conference} before the child {@link Connection}s are merged. This is how
     * CDMA-based {@link Connection}s are implemented. For these unmerged {@link Conference}s, this
     * capability allows a merge button to be shown while the conference is in the foreground
     * of the in-call UI.
     * <p>
     * This is only intended for use by a {@link Conference}.
     */
    public static final int CAPABILITY_MERGE_CONFERENCE = 0x00000004;

    
Connections within a conference can be swapped between foreground and background. See CAPABILITY_MERGE_CONFERENCE for additional information. 
 This is only intended for use by a Conference. /**
     * Connections within a conference can be swapped between foreground and background.
     * See {@link #CAPABILITY_MERGE_CONFERENCE} for additional information.
     * <p>
     * This is only intended for use by a {@link Conference}.
     */
    public static final int CAPABILITY_SWAP_CONFERENCE = 0x00000008;

    
@hide
/**
     * @hide
     */
    public static final int CAPABILITY_UNUSED = 0x00000010;

    
Connection supports responding via text option. /** Connection supports responding via text option. */
    public static final int CAPABILITY_RESPOND_VIA_TEXT = 0x00000020;

    
Connection can be muted. /** Connection can be muted. */
    public static final int CAPABILITY_MUTE = 0x00000040;

    
Connection supports conference management. This capability only applies to Conferences which can have Connections as children. /**
     * Connection supports conference management. This capability only applies to
     * {@link Conference}s which can have {@link Connection}s as children.
     */
    public static final int CAPABILITY_MANAGE_CONFERENCE = 0x00000080;

    
Local device supports receiving video.
/**
     * Local device supports receiving video.
     */
    public static final int CAPABILITY_SUPPORTS_VT_LOCAL_RX = 0x00000100;

    
Local device supports transmitting video.
/**
     * Local device supports transmitting video.
     */
    public static final int CAPABILITY_SUPPORTS_VT_LOCAL_TX = 0x00000200;

    
Local device supports bidirectional video calling.
/**
     * Local device supports bidirectional video calling.
     */
    public static final int CAPABILITY_SUPPORTS_VT_LOCAL_BIDIRECTIONAL =
            CAPABILITY_SUPPORTS_VT_LOCAL_RX | CAPABILITY_SUPPORTS_VT_LOCAL_TX;

    
Remote device supports receiving video.
/**
     * Remote device supports receiving video.
     */
    public static final int CAPABILITY_SUPPORTS_VT_REMOTE_RX = 0x00000400;

    
Remote device supports transmitting video.
/**
     * Remote device supports transmitting video.
     */
    public static final int CAPABILITY_SUPPORTS_VT_REMOTE_TX = 0x00000800;

    
Remote device supports bidirectional video calling.
/**
     * Remote device supports bidirectional video calling.
     */
    public static final int CAPABILITY_SUPPORTS_VT_REMOTE_BIDIRECTIONAL =
            CAPABILITY_SUPPORTS_VT_REMOTE_RX | CAPABILITY_SUPPORTS_VT_REMOTE_TX;

    
Connection is able to be separated from its parent Conference, if any. /**
     * Connection is able to be separated from its parent {@code Conference}, if any.
     */
    public static final int CAPABILITY_SEPARATE_FROM_CONFERENCE = 0x00001000;

    
Connection is able to be individually disconnected when in a Conference. /**
     * Connection is able to be individually disconnected when in a {@code Conference}.
     */
    public static final int CAPABILITY_DISCONNECT_FROM_CONFERENCE = 0x00002000;

    
Un-used.
@hide
/**
     * Un-used.
     * @hide
     */
    public static final int CAPABILITY_UNUSED_2 = 0x00004000;

    
Un-used.
@hide
/**
     * Un-used.
     * @hide
     */
    public static final int CAPABILITY_UNUSED_3 = 0x00008000;

    
Un-used.
@hide
/**
     * Un-used.
     * @hide
     */
    public static final int CAPABILITY_UNUSED_4 = 0x00010000;

    
Un-used.
@hide
/**
     * Un-used.
     * @hide
     */
    public static final int CAPABILITY_UNUSED_5 = 0x00020000;

    
Speed up audio setup for MT call.
@hide
/**
     * Speed up audio setup for MT call.
     * @hide
     */
    public static final int CAPABILITY_SPEED_UP_MT_AUDIO = 0x00040000;

    
Call can be upgraded to a video call.
/**
     * Call can be upgraded to a video call.
     */
    public static final int CAPABILITY_CAN_UPGRADE_TO_VIDEO = 0x00080000;

    
For video calls, indicates whether the outgoing video for the call can be paused using the VideoProfile.STATE_PAUSED VideoState. /**
     * For video calls, indicates whether the outgoing video for the call can be paused using
     * the {@link android.telecom.VideoProfile#STATE_PAUSED} VideoState.
     */
    public static final int CAPABILITY_CAN_PAUSE_VIDEO = 0x00100000;

    
For a conference, indicates the conference will not have child connections.

An example of a conference with child connections is a GSM conference call, where the radio
retains connections to the individual participants of the conference.  Another example is an
IMS conference call where conference event package functionality is supported; in this case
the conference server ensures the radio is aware of the participants in the conference, which
are represented by child connections.

An example of a conference with no child connections is an IMS conference call with no
conference event package support.  Such a conference is represented by the radio as a single
connection to the IMS conference server.

Indicating whether a conference has children or not is important to help user interfaces
visually represent a conference.  A conference with no children, for example, will have the
conference connection shown in the list of calls on a Bluetooth device, where if the
conference has children, only the children will be shown in the list of calls on a Bluetooth
device.
@hide
/**
     * For a conference, indicates the conference will not have child connections.
     * <p>
     * An example of a conference with child connections is a GSM conference call, where the radio
     * retains connections to the individual participants of the conference.  Another example is an
     * IMS conference call where conference event package functionality is supported; in this case
     * the conference server ensures the radio is aware of the participants in the conference, which
     * are represented by child connections.
     * <p>
     * An example of a conference with no child connections is an IMS conference call with no
     * conference event package support.  Such a conference is represented by the radio as a single
     * connection to the IMS conference server.
     * <p>
     * Indicating whether a conference has children or not is important to help user interfaces
     * visually represent a conference.  A conference with no children, for example, will have the
     * conference connection shown in the list of calls on a Bluetooth device, where if the
     * conference has children, only the children will be shown in the list of calls on a Bluetooth
     * device.
     * @hide
     */
    public static final int CAPABILITY_CONFERENCE_HAS_NO_CHILDREN = 0x00200000;

    
Indicates that the connection itself wants to handle any sort of reply response, rather than
relying on SMS.
/**
     * Indicates that the connection itself wants to handle any sort of reply response, rather than
     * relying on SMS.
     */
    public static final int CAPABILITY_CAN_SEND_RESPONSE_VIA_CONNECTION = 0x00400000;

    
When set, prevents a video call from being downgraded to an audio-only call.
 Should be set when the VideoState has the VideoProfile.STATE_TX_ENABLED or VideoProfile.STATE_RX_ENABLED bits set to indicate that the connection cannot be downgraded from a video call back to a VideoState of VideoProfile.STATE_AUDIO_ONLY. 
 Intuitively, a call which can be downgraded to audio should also have local and remote video capabilities (see CAPABILITY_SUPPORTS_VT_LOCAL_BIDIRECTIONAL and CAPABILITY_SUPPORTS_VT_REMOTE_BIDIRECTIONAL). /**
     * When set, prevents a video call from being downgraded to an audio-only call.
     * <p>
     * Should be set when the VideoState has the {@link VideoProfile#STATE_TX_ENABLED} or
     * {@link VideoProfile#STATE_RX_ENABLED} bits set to indicate that the connection cannot be
     * downgraded from a video call back to a VideoState of
     * {@link VideoProfile#STATE_AUDIO_ONLY}.
     * <p>
     * Intuitively, a call which can be downgraded to audio should also have local and remote
     * video
     * capabilities (see {@link #CAPABILITY_SUPPORTS_VT_LOCAL_BIDIRECTIONAL} and
     * {@link #CAPABILITY_SUPPORTS_VT_REMOTE_BIDIRECTIONAL}).
     */
    public static final int CAPABILITY_CANNOT_DOWNGRADE_VIDEO_TO_AUDIO = 0x00800000;

    
When set for an external connection, indicates that this Connection can be pulled from a remote device to the current device. 
 Should only be set on a Connection where PROPERTY_IS_EXTERNAL_CALL is set. /**
     * When set for an external connection, indicates that this {@code Connection} can be pulled
     * from a remote device to the current device.
     * <p>
     * Should only be set on a {@code Connection} where {@link #PROPERTY_IS_EXTERNAL_CALL}
     * is set.
     */
    public static final int CAPABILITY_CAN_PULL_CALL = 0x01000000;

    
Call supports the deflect feature. /** Call supports the deflect feature. */
    public static final int CAPABILITY_SUPPORT_DEFLECT = 0x02000000;

    //**********************************************************************************************
    // Next CAPABILITY value: 0x04000000
    //**********************************************************************************************

    
Indicates that the current device callback number should be shown.
@hide
/**
     * Indicates that the current device callback number should be shown.
     *
     * @hide
     */
    public static final int PROPERTY_EMERGENCY_CALLBACK_MODE = 1<<0;

    
Whether the call is a generic conference, where we do not know the precise state of
participants in the conference (eg. on CDMA).
@hide
/**
     * Whether the call is a generic conference, where we do not know the precise state of
     * participants in the conference (eg. on CDMA).
     *
     * @hide
     */
    public static final int PROPERTY_GENERIC_CONFERENCE = 1<<1;

    
Connection is using high definition audio.
@hide
/**
     * Connection is using high definition audio.
     * @hide
     */
    public static final int PROPERTY_HIGH_DEF_AUDIO = 1<<2;

    
Connection is using WIFI.
@hide
/**
     * Connection is using WIFI.
     * @hide
     */
    public static final int PROPERTY_WIFI = 1<<3;

    
When set, indicates that the Connection does not actually exist locally for the ConnectionService. 
 Consider, for example, a scenario where a user has two devices with the same phone number. When a user places a call on one devices, the telephony stack can represent that call on the other device by adding is to the ConnectionService with the PROPERTY_IS_EXTERNAL_CALL capability set. 
 An ConnectionService should not assume that all InCallServices will handle external connections. Only those InCallServices which have the TelecomManager.METADATA_INCLUDE_EXTERNAL_CALLS metadata set to true in its manifest will see external connections. /**
     * When set, indicates that the {@code Connection} does not actually exist locally for the
     * {@link ConnectionService}.
     * <p>
     * Consider, for example, a scenario where a user has two devices with the same phone number.
     * When a user places a call on one devices, the telephony stack can represent that call on the
     * other device by adding is to the {@link ConnectionService} with the
     * {@link #PROPERTY_IS_EXTERNAL_CALL} capability set.
     * <p>
     * An {@link ConnectionService} should not assume that all {@link InCallService}s will handle
     * external connections.  Only those {@link InCallService}s which have the
     * {@link TelecomManager#METADATA_INCLUDE_EXTERNAL_CALLS} metadata set to {@code true} in its
     * manifest will see external connections.
     */
    public static final int PROPERTY_IS_EXTERNAL_CALL = 1<<4;

    
Indicates that the connection has CDMA Enhanced Voice Privacy enabled.
/**
     * Indicates that the connection has CDMA Enhanced Voice Privacy enabled.
     */
    public static final int PROPERTY_HAS_CDMA_VOICE_PRIVACY = 1<<5;

    
Indicates that the connection represents a downgraded IMS conference.
@hide
/**
     * Indicates that the connection represents a downgraded IMS conference.
     * @hide
     */
    public static final int PROPERTY_IS_DOWNGRADED_CONFERENCE = 1<<6;

    
Set by the framework to indicate that the Connection originated from a self-managed ConnectionService. 
 See PhoneAccount.CAPABILITY_SELF_MANAGED. /**
     * Set by the framework to indicate that the {@link Connection} originated from a self-managed
     * {@link ConnectionService}.
     * <p>
     * See {@link PhoneAccount#CAPABILITY_SELF_MANAGED}.
     */
    public static final int PROPERTY_SELF_MANAGED = 1<<7;

    
Set by the framework to indicate that a connection has an active RTT session associated with
it.
/**
     * Set by the framework to indicate that a connection has an active RTT session associated with
     * it.
     */
    public static final int PROPERTY_IS_RTT = 1 << 8;

    
Set by the framework to indicate that a connection is using assisted dialing.
@hide
/**
     * Set by the framework to indicate that a connection is using assisted dialing.
     * @hide
     */
    public static final int PROPERTY_ASSISTED_DIALING_USED = 1 << 9;

    //**********************************************************************************************
    // Next PROPERTY value: 1<<10
    //**********************************************************************************************

    
Connection extra key used to store the last forwarded number associated with the current
connection.  Used to communicate to the user interface that the connection was forwarded via
the specified number.
/**
     * Connection extra key used to store the last forwarded number associated with the current
     * connection.  Used to communicate to the user interface that the connection was forwarded via
     * the specified number.
     */
    public static final String EXTRA_LAST_FORWARDED_NUMBER =
            "android.telecom.extra.LAST_FORWARDED_NUMBER";

    
Connection extra key used to store a child number associated with the current connection. Used to communicate to the user interface that the connection was received via a child address (i.e. phone number) associated with the PhoneAccount's primary address. /**
     * Connection extra key used to store a child number associated with the current connection.
     * Used to communicate to the user interface that the connection was received via
     * a child address (i.e. phone number) associated with the {@link PhoneAccount}'s primary
     * address.
     */
    public static final String EXTRA_CHILD_ADDRESS = "android.telecom.extra.CHILD_ADDRESS";

    
Connection extra key used to store the subject for an incoming call. The user interface can query this extra and display its contents for incoming calls. Will only be used if the PhoneAccount supports the capability PhoneAccount.CAPABILITY_CALL_SUBJECT. /**
     * Connection extra key used to store the subject for an incoming call.  The user interface can
     * query this extra and display its contents for incoming calls.  Will only be used if the
     * {@link PhoneAccount} supports the capability {@link PhoneAccount#CAPABILITY_CALL_SUBJECT}.
     */
    public static final String EXTRA_CALL_SUBJECT = "android.telecom.extra.CALL_SUBJECT";

    
Boolean connection extra key set on a Connection in STATE_RINGING state to indicate that answering the call will cause the current active foreground call to be dropped. /**
     * Boolean connection extra key set on a {@link Connection} in
     * {@link Connection#STATE_RINGING} state to indicate that answering the call will cause the
     * current active foreground call to be dropped.
     */
    public static final String EXTRA_ANSWERING_DROPS_FG_CALL =
            "android.telecom.extra.ANSWERING_DROPS_FG_CALL";

    
String connection extra key set on a Connection in STATE_RINGING state to indicate the name of the third-party app which is responsible for the current foreground call. 
 Used when EXTRA_ANSWERING_DROPS_FG_CALL is true to ensure that the default Phone app is able to inform the user that answering the new incoming call will cause a call owned by another app to be dropped when the incoming call is answered. /**
     * String connection extra key set on a {@link Connection} in {@link Connection#STATE_RINGING}
     * state to indicate the name of the third-party app which is responsible for the current
     * foreground call.
     * <p>
     * Used when {@link #EXTRA_ANSWERING_DROPS_FG_CALL} is true to ensure that the default Phone app
     * is able to inform the user that answering the new incoming call will cause a call owned by
     * another app to be dropped when the incoming call is answered.
     */
    public static final String EXTRA_ANSWERING_DROPS_FG_CALL_APP_NAME =
            "android.telecom.extra.ANSWERING_DROPS_FG_CALL_APP_NAME";

    
Boolean connection extra key on a Connection which indicates that adding an additional call is disallowed. 
@hide
/**
     * Boolean connection extra key on a {@link Connection} which indicates that adding an
     * additional call is disallowed.
     * @hide
     */
    public static final String EXTRA_DISABLE_ADD_CALL =
            "android.telecom.extra.DISABLE_ADD_CALL";

    
String connection extra key on a Connection or Conference which contains the original Connection ID associated with the connection. Used in RemoteConnectionService to track the Connection ID which was originally assigned to a connection/conference added via ConnectionService.addExistingConnection(PhoneAccountHandle, Connection) and ConnectionService.addConference(Conference) APIs. This is important to pass to Telecom for when it deals with RemoteConnections. When the ConnectionManager wraps the RemoteConnection and RemoteConference and adds it to Telecom, there needs to be a way to ensure that we don't add the connection again as a duplicate. 
 For example, the TelephonyCS calls addExistingConnection for a Connection with ID TelephonyCS@1. The ConnectionManager learns of this via ConnectionService.onRemoteExistingConnectionAdded(RemoteConnection), and wraps this in a new Connection which it adds to Telecom via ConnectionService.addExistingConnection(PhoneAccountHandle, Connection). As part of this process, the wrapped RemoteConnection gets assigned a new ID (e.g. ConnMan@1). The TelephonyCS will ALSO try to add the existing connection to Telecom, except with the ID it originally referred to the connection as. Thus Telecom needs to know that the Connection with ID ConnMan@1 is really the same as TelephonyCS@1. 
@hide
/**
     * String connection extra key on a {@link Connection} or {@link Conference} which contains the
     * original Connection ID associated with the connection.  Used in
     * {@link RemoteConnectionService} to track the Connection ID which was originally assigned to a
     * connection/conference added via
     * {@link ConnectionService#addExistingConnection(PhoneAccountHandle, Connection)} and
     * {@link ConnectionService#addConference(Conference)} APIs.  This is important to pass to
     * Telecom for when it deals with RemoteConnections.  When the ConnectionManager wraps the
     * {@link RemoteConnection} and {@link RemoteConference} and adds it to Telecom, there needs to
     * be a way to ensure that we don't add the connection again as a duplicate.
     * <p>
     * For example, the TelephonyCS calls addExistingConnection for a Connection with ID
     * {@code TelephonyCS@1}.  The ConnectionManager learns of this via
     * {@link ConnectionService#onRemoteExistingConnectionAdded(RemoteConnection)}, and wraps this
     * in a new {@link Connection} which it adds to Telecom via
     * {@link ConnectionService#addExistingConnection(PhoneAccountHandle, Connection)}.  As part of
     * this process, the wrapped RemoteConnection gets assigned a new ID (e.g. {@code ConnMan@1}).
     * The TelephonyCS will ALSO try to add the existing connection to Telecom, except with the
     * ID it originally referred to the connection as.  Thus Telecom needs to know that the
     * Connection with ID {@code ConnMan@1} is really the same as {@code TelephonyCS@1}.
     * @hide
     */
    public static final String EXTRA_ORIGINAL_CONNECTION_ID =
            "android.telecom.extra.ORIGINAL_CONNECTION_ID";

    
Connection event used to inform Telecom that it should play the on hold tone. This is used to play a tone when the peer puts the current call on hold. Sent to Telecom via sendConnectionEvent(String, Bundle). 
@hide
/**
     * Connection event used to inform Telecom that it should play the on hold tone.  This is used
     * to play a tone when the peer puts the current call on hold.  Sent to Telecom via
     * {@link #sendConnectionEvent(String, Bundle)}.
     * @hide
     */
    public static final String EVENT_ON_HOLD_TONE_START =
            "android.telecom.event.ON_HOLD_TONE_START";

    
Connection event used to inform Telecom that it should stop the on hold tone. This is used to stop a tone when the peer puts the current call on hold. Sent to Telecom via sendConnectionEvent(String, Bundle). 
@hide
/**
     * Connection event used to inform Telecom that it should stop the on hold tone.  This is used
     * to stop a tone when the peer puts the current call on hold.  Sent to Telecom via
     * {@link #sendConnectionEvent(String, Bundle)}.
     * @hide
     */
    public static final String EVENT_ON_HOLD_TONE_END =
            "android.telecom.event.ON_HOLD_TONE_END";

    
Connection event used to inform InCallServices when pulling of an external call has failed. The user interface should inform the user of the error. 
 Expected to be used by the ConnectionService when the Call.pullExternalCall() API is called on a Call with the properties Details.PROPERTY_IS_EXTERNAL_CALL and Details.CAPABILITY_CAN_PULL_CALL, but the ConnectionService could not pull the external call due to an error condition. 
 Sent via sendConnectionEvent(String, Bundle). The Bundle parameter is expected to be null when this connection event is used. /**
     * Connection event used to inform {@link InCallService}s when pulling of an external call has
     * failed.  The user interface should inform the user of the error.
     * <p>
     * Expected to be used by the {@link ConnectionService} when the {@link Call#pullExternalCall()}
     * API is called on a {@link Call} with the properties
     * {@link Call.Details#PROPERTY_IS_EXTERNAL_CALL} and
     * {@link Call.Details#CAPABILITY_CAN_PULL_CALL}, but the {@link ConnectionService} could not
     * pull the external call due to an error condition.
     * <p>
     * Sent via {@link #sendConnectionEvent(String, Bundle)}.  The {@link Bundle} parameter is
     * expected to be null when this connection event is used.
     */
    public static final String EVENT_CALL_PULL_FAILED = "android.telecom.event.CALL_PULL_FAILED";

    
Connection event used to inform InCallServices when the merging of two calls has failed. The User Interface should use this message to inform the user of the error. 
 Sent via sendConnectionEvent(String, Bundle). The Bundle parameter is expected to be null when this connection event is used. /**
     * Connection event used to inform {@link InCallService}s when the merging of two calls has
     * failed. The User Interface should use this message to inform the user of the error.
     * <p>
     * Sent via {@link #sendConnectionEvent(String, Bundle)}.  The {@link Bundle} parameter is
     * expected to be null when this connection event is used.
     */
    public static final String EVENT_CALL_MERGE_FAILED = "android.telecom.event.CALL_MERGE_FAILED";

    
Connection event used to inform InCallServices when the process of merging a Connection into a conference has begun. 
 Sent via sendConnectionEvent(String, Bundle). The Bundle parameter is expected to be null when this connection event is used. 
@hide
/**
     * Connection event used to inform {@link InCallService}s when the process of merging a
     * Connection into a conference has begun.
     * <p>
     * Sent via {@link #sendConnectionEvent(String, Bundle)}.  The {@link Bundle} parameter is
     * expected to be null when this connection event is used.
     * @hide
     */
    public static final String EVENT_MERGE_START = "android.telecom.event.MERGE_START";

    
Connection event used to inform InCallServices when the process of merging a Connection into a conference has completed. 
 Sent via sendConnectionEvent(String, Bundle). The Bundle parameter is expected to be null when this connection event is used. 
@hide
/**
     * Connection event used to inform {@link InCallService}s when the process of merging a
     * Connection into a conference has completed.
     * <p>
     * Sent via {@link #sendConnectionEvent(String, Bundle)}.  The {@link Bundle} parameter is
     * expected to be null when this connection event is used.
     * @hide
     */
    public static final String EVENT_MERGE_COMPLETE = "android.telecom.event.MERGE_COMPLETE";

    
Connection event used to inform InCallServices when a call has been put on hold by the remote party. 
 This is different than the STATE_HOLDING state which indicates that the call is being held locally on the device. When a capable ConnectionService receives signalling to indicate that the remote party has put the call on hold, it can send this connection event. 
@hide
/**
     * Connection event used to inform {@link InCallService}s when a call has been put on hold by
     * the remote party.
     * <p>
     * This is different than the {@link Connection#STATE_HOLDING} state which indicates that the
     * call is being held locally on the device.  When a capable {@link ConnectionService} receives
     * signalling to indicate that the remote party has put the call on hold, it can send this
     * connection event.
     * @hide
     */
    public static final String EVENT_CALL_REMOTELY_HELD =
            "android.telecom.event.CALL_REMOTELY_HELD";

    
Connection event used to inform InCallServices when a call which was remotely held (see EVENT_CALL_REMOTELY_HELD) has been un-held by the remote party. 
 This is different than the STATE_HOLDING state which indicates that the call is being held locally on the device. When a capable ConnectionService receives signalling to indicate that the remote party has taken the call off hold, it can send this connection event. 
@hide
/**
     * Connection event used to inform {@link InCallService}s when a call which was remotely held
     * (see {@link #EVENT_CALL_REMOTELY_HELD}) has been un-held by the remote party.
     * <p>
     * This is different than the {@link Connection#STATE_HOLDING} state which indicates that the
     * call is being held locally on the device.  When a capable {@link ConnectionService} receives
     * signalling to indicate that the remote party has taken the call off hold, it can send this
     * connection event.
     * @hide
     */
    public static final String EVENT_CALL_REMOTELY_UNHELD =
            "android.telecom.event.CALL_REMOTELY_UNHELD";

    
Connection event used to inform an InCallService which initiated a call handover via Call.EVENT_REQUEST_HANDOVER that the handover from this Connection has successfully completed. 
@hide
/**
     * Connection event used to inform an {@link InCallService} which initiated a call handover via
     * {@link Call#EVENT_REQUEST_HANDOVER} that the handover from this {@link Connection} has
     * successfully completed.
     * @hide
     */
    public static final String EVENT_HANDOVER_COMPLETE =
            "android.telecom.event.HANDOVER_COMPLETE";

    
Connection event used to inform an InCallService which initiated a call handover via Call.EVENT_REQUEST_HANDOVER that the handover from this Connection has failed to complete. 
@hide
/**
     * Connection event used to inform an {@link InCallService} which initiated a call handover via
     * {@link Call#EVENT_REQUEST_HANDOVER} that the handover from this {@link Connection} has failed
     * to complete.
     * @hide
     */
    public static final String EVENT_HANDOVER_FAILED =
            "android.telecom.event.HANDOVER_FAILED";

    // Flag controlling whether PII is emitted into the logs
    private static final boolean PII_DEBUG = Log.isLoggable(android.util.Log.DEBUG);

    
Whether the given capabilities support the specified capability.
Params:
capabilities – A capability bit field.
capability – The capability to check capabilities for.
Returns:
Whether the specified capability is supported.
@hide
/**
     * Whether the given capabilities support the specified capability.
     *
     * @param capabilities A capability bit field.
     * @param capability The capability to check capabilities for.
     * @return Whether the specified capability is supported.
     * @hide
     */
    public static boolean can(int capabilities, int capability) {
        return (capabilities & capability) == capability;
    }

    
Whether the capabilities of this Connection supports the specified capability. 
Params:
capability – The capability to check capabilities for.
Returns:
Whether the specified capability is supported.
@hide
/**
     * Whether the capabilities of this {@code Connection} supports the specified capability.
     *
     * @param capability The capability to check capabilities for.
     * @return Whether the specified capability is supported.
     * @hide
     */
    public boolean can(int capability) {
        return can(mConnectionCapabilities, capability);
    }

    
Removes the specified capability from the set of capabilities of this Connection. 
Params:
capability – The capability to remove from the set.
@hide
/**
     * Removes the specified capability from the set of capabilities of this {@code Connection}.
     *
     * @param capability The capability to remove from the set.
     * @hide
     */
    public void removeCapability(int capability) {
        mConnectionCapabilities &= ~capability;
    }

    
Adds the specified capability to the set of capabilities of this Connection. 
Params:
capability – The capability to add to the set.
@hide
/**
     * Adds the specified capability to the set of capabilities of this {@code Connection}.
     *
     * @param capability The capability to add to the set.
     * @hide
     */
    public void addCapability(int capability) {
        mConnectionCapabilities |= capability;
    }

    
Renders a set of capability bits (CAPABILITY_*) as a human readable string. 
Params:
capabilities – A capability bit field.
Returns:
A human readable string representation./**
     * Renders a set of capability bits ({@code CAPABILITY_*}) as a human readable string.
     *
     * @param capabilities A capability bit field.
     * @return A human readable string representation.
     */
    public static String capabilitiesToString(int capabilities) {
        return capabilitiesToStringInternal(capabilities, true /* isLong */);
    }

    
Renders a set of capability bits (CAPABILITY_*) as a *short* human readable string. 
Params:
capabilities – A capability bit field.
Returns:
A human readable string representation.
@hide
/**
     * Renders a set of capability bits ({@code CAPABILITY_*}) as a *short* human readable
     * string.
     *
     * @param capabilities A capability bit field.
     * @return A human readable string representation.
     * @hide
     */
    public static String capabilitiesToStringShort(int capabilities) {
        return capabilitiesToStringInternal(capabilities, false /* isLong */);
    }

    private static String capabilitiesToStringInternal(int capabilities, boolean isLong) {
        StringBuilder builder = new StringBuilder();
        builder.append("[");
        if (isLong) {
            builder.append("Capabilities:");
        }

        if (can(capabilities, CAPABILITY_HOLD)) {
            builder.append(isLong ? " CAPABILITY_HOLD" : " hld");
        }
        if (can(capabilities, CAPABILITY_SUPPORT_HOLD)) {
            builder.append(isLong ? " CAPABILITY_SUPPORT_HOLD" : " sup_hld");
        }
        if (can(capabilities, CAPABILITY_MERGE_CONFERENCE)) {
            builder.append(isLong ? " CAPABILITY_MERGE_CONFERENCE" : " mrg_cnf");
        }
        if (can(capabilities, CAPABILITY_SWAP_CONFERENCE)) {
            builder.append(isLong ? " CAPABILITY_SWAP_CONFERENCE" : " swp_cnf");
        }
        if (can(capabilities, CAPABILITY_RESPOND_VIA_TEXT)) {
            builder.append(isLong ? " CAPABILITY_RESPOND_VIA_TEXT" : " txt");
        }
        if (can(capabilities, CAPABILITY_MUTE)) {
            builder.append(isLong ? " CAPABILITY_MUTE" : " mut");
        }
        if (can(capabilities, CAPABILITY_MANAGE_CONFERENCE)) {
            builder.append(isLong ? " CAPABILITY_MANAGE_CONFERENCE" : " mng_cnf");
        }
        if (can(capabilities, CAPABILITY_SUPPORTS_VT_LOCAL_RX)) {
            builder.append(isLong ? " CAPABILITY_SUPPORTS_VT_LOCAL_RX" : " VTlrx");
        }
        if (can(capabilities, CAPABILITY_SUPPORTS_VT_LOCAL_TX)) {
            builder.append(isLong ? " CAPABILITY_SUPPORTS_VT_LOCAL_TX" : " VTltx");
        }
        if (can(capabilities, CAPABILITY_SUPPORTS_VT_LOCAL_BIDIRECTIONAL)) {
            builder.append(isLong ? " CAPABILITY_SUPPORTS_VT_LOCAL_BIDIRECTIONAL" : " VTlbi");
        }
        if (can(capabilities, CAPABILITY_SUPPORTS_VT_REMOTE_RX)) {
            builder.append(isLong ? " CAPABILITY_SUPPORTS_VT_REMOTE_RX" : " VTrrx");
        }
        if (can(capabilities, CAPABILITY_SUPPORTS_VT_REMOTE_TX)) {
            builder.append(isLong ? " CAPABILITY_SUPPORTS_VT_REMOTE_TX" : " VTrtx");
        }
        if (can(capabilities, CAPABILITY_SUPPORTS_VT_REMOTE_BIDIRECTIONAL)) {
            builder.append(isLong ? " CAPABILITY_SUPPORTS_VT_REMOTE_BIDIRECTIONAL" : " VTrbi");
        }
        if (can(capabilities, CAPABILITY_CANNOT_DOWNGRADE_VIDEO_TO_AUDIO)) {
            builder.append(isLong ? " CAPABILITY_CANNOT_DOWNGRADE_VIDEO_TO_AUDIO" : " !v2a");
        }
        if (can(capabilities, CAPABILITY_SPEED_UP_MT_AUDIO)) {
            builder.append(isLong ? " CAPABILITY_SPEED_UP_MT_AUDIO" : " spd_aud");
        }
        if (can(capabilities, CAPABILITY_CAN_UPGRADE_TO_VIDEO)) {
            builder.append(isLong ? " CAPABILITY_CAN_UPGRADE_TO_VIDEO" : " a2v");
        }
        if (can(capabilities, CAPABILITY_CAN_PAUSE_VIDEO)) {
            builder.append(isLong ? " CAPABILITY_CAN_PAUSE_VIDEO" : " paus_VT");
        }
        if (can(capabilities, CAPABILITY_CONFERENCE_HAS_NO_CHILDREN)) {
            builder.append(isLong ? " CAPABILITY_SINGLE_PARTY_CONFERENCE" : " 1p_cnf");
        }
        if (can(capabilities, CAPABILITY_CAN_SEND_RESPONSE_VIA_CONNECTION)) {
            builder.append(isLong ? " CAPABILITY_CAN_SEND_RESPONSE_VIA_CONNECTION" : " rsp_by_con");
        }
        if (can(capabilities, CAPABILITY_CAN_PULL_CALL)) {
            builder.append(isLong ? " CAPABILITY_CAN_PULL_CALL" : " pull");
        }
        if (can(capabilities, CAPABILITY_SUPPORT_DEFLECT)) {
            builder.append(isLong ? " CAPABILITY_SUPPORT_DEFLECT" : " sup_def");
        }

        builder.append("]");
        return builder.toString();
    }

    
Renders a set of property bits (PROPERTY_*) as a human readable string. 
Params:
properties – A property bit field.
Returns:
A human readable string representation./**
     * Renders a set of property bits ({@code PROPERTY_*}) as a human readable string.
     *
     * @param properties A property bit field.
     * @return A human readable string representation.
     */
    public static String propertiesToString(int properties) {
        return propertiesToStringInternal(properties, true /* isLong */);
    }

    
Renders a set of property bits (PROPERTY_*) as a *short* human readable string. 
Params:
properties – A property bit field.
Returns:
A human readable string representation.
@hide
/**
     * Renders a set of property bits ({@code PROPERTY_*}) as a *short* human readable string.
     *
     * @param properties A property bit field.
     * @return A human readable string representation.
     * @hide
     */
    public static String propertiesToStringShort(int properties) {
        return propertiesToStringInternal(properties, false /* isLong */);
    }

    private static String propertiesToStringInternal(int properties, boolean isLong) {
        StringBuilder builder = new StringBuilder();
        builder.append("[");
        if (isLong) {
            builder.append("Properties:");
        }

        if (can(properties, PROPERTY_SELF_MANAGED)) {
            builder.append(isLong ? " PROPERTY_SELF_MANAGED" : " self_mng");
        }

        if (can(properties, PROPERTY_EMERGENCY_CALLBACK_MODE)) {
            builder.append(isLong ? " PROPERTY_EMERGENCY_CALLBACK_MODE" : " ecbm");
        }

        if (can(properties, PROPERTY_HIGH_DEF_AUDIO)) {
            builder.append(isLong ? " PROPERTY_HIGH_DEF_AUDIO" : " HD");
        }

        if (can(properties, PROPERTY_WIFI)) {
            builder.append(isLong ? " PROPERTY_WIFI" : " wifi");
        }

        if (can(properties, PROPERTY_GENERIC_CONFERENCE)) {
            builder.append(isLong ? " PROPERTY_GENERIC_CONFERENCE" : " gen_conf");
        }

        if (can(properties, PROPERTY_IS_EXTERNAL_CALL)) {
            builder.append(isLong ? " PROPERTY_IS_EXTERNAL_CALL" : " xtrnl");
        }

        if (can(properties, PROPERTY_HAS_CDMA_VOICE_PRIVACY)) {
            builder.append(isLong ? " PROPERTY_HAS_CDMA_VOICE_PRIVACY" : " priv");
        }

        if (can(properties, PROPERTY_IS_RTT)) {
            builder.append(isLong ? " PROPERTY_IS_RTT" : " rtt");
        }

        builder.append("]");
        return builder.toString();
    }

    
@hide
/** @hide */
    public abstract static class Listener {
        public void onStateChanged(Connection c, int state) {}
        public void onAddressChanged(Connection c, Uri newAddress, int presentation) {}
        public void onCallerDisplayNameChanged(
                Connection c, String callerDisplayName, int presentation) {}
        public void onVideoStateChanged(Connection c, int videoState) {}
        public void onDisconnected(Connection c, DisconnectCause disconnectCause) {}
        public void onPostDialWait(Connection c, String remaining) {}
        public void onPostDialChar(Connection c, char nextChar) {}
        public void onRingbackRequested(Connection c, boolean ringback) {}
        public void onDestroyed(Connection c) {}
        public void onConnectionCapabilitiesChanged(Connection c, int capabilities) {}
        public void onConnectionPropertiesChanged(Connection c, int properties) {}
        public void onSupportedAudioRoutesChanged(Connection c, int supportedAudioRoutes) {}
        public void onVideoProviderChanged(
                Connection c, VideoProvider videoProvider) {}
        public void onAudioModeIsVoipChanged(Connection c, boolean isVoip) {}
        public void onStatusHintsChanged(Connection c, StatusHints statusHints) {}
        public void onConferenceablesChanged(
                Connection c, List<Conferenceable> conferenceables) {}
        public void onConferenceChanged(Connection c, Conference conference) {}
        
@hide
/** @hide */
        public void onConferenceParticipantsChanged(Connection c,
                List<ConferenceParticipant> participants) {}
        public void onConferenceStarted() {}
        public void onConferenceMergeFailed(Connection c) {}
        public void onExtrasChanged(Connection c, Bundle extras) {}
        public void onExtrasRemoved(Connection c, List<String> keys) {}
        public void onConnectionEvent(Connection c, String event, Bundle extras) {}
        
@hide
/** @hide */
        public void onConferenceSupportedChanged(Connection c, boolean isConferenceSupported) {}
        public void onAudioRouteChanged(Connection c, int audioRoute, String bluetoothAddress) {}
        public void onRttInitiationSuccess(Connection c) {}
        public void onRttInitiationFailure(Connection c, int reason) {}
        public void onRttSessionRemotelyTerminated(Connection c) {}
        public void onRemoteRttRequest(Connection c) {}
        
@hide
/** @hide */
        public void onPhoneAccountChanged(Connection c, PhoneAccountHandle pHandle) {}
    }

    
Provides methods to read and write RTT data to/from the in-call app.
/**
     * Provides methods to read and write RTT data to/from the in-call app.
     */
    public static final class RttTextStream {
        private static final int READ_BUFFER_SIZE = 1000;
        private final InputStreamReader mPipeFromInCall;
        private final OutputStreamWriter mPipeToInCall;
        private final ParcelFileDescriptor mFdFromInCall;
        private final ParcelFileDescriptor mFdToInCall;

        private final FileInputStream mFromInCallFileInputStream;
        private char[] mReadBuffer = new char[READ_BUFFER_SIZE];

        
@hide
/**
         * @hide
         */
        public RttTextStream(ParcelFileDescriptor toInCall, ParcelFileDescriptor fromInCall) {
            mFdFromInCall = fromInCall;
            mFdToInCall = toInCall;
            mFromInCallFileInputStream = new FileInputStream(fromInCall.getFileDescriptor());

            // Wrap the FileInputStream in a Channel so that it's interruptible.
            mPipeFromInCall = new InputStreamReader(
                    Channels.newInputStream(Channels.newChannel(mFromInCallFileInputStream)));
            mPipeToInCall = new OutputStreamWriter(
                    new FileOutputStream(toInCall.getFileDescriptor()));
        }

        
Writes the string {@param input} into the text stream to the UI for this RTT call. Since
RTT transmits text in real-time, this method should be called as often as text snippets
are received from the remote user, even if it is only one character.

This method is not thread-safe -- calling it from multiple threads simultaneously may
lead to interleaved text.
Params:
input – The message to send to the in-call app./**
         * Writes the string {@param input} into the text stream to the UI for this RTT call. Since
         * RTT transmits text in real-time, this method should be called as often as text snippets
         * are received from the remote user, even if it is only one character.
         * <p>
         * This method is not thread-safe -- calling it from multiple threads simultaneously may
         * lead to interleaved text.
         *
         * @param input The message to send to the in-call app.
         */
        public void write(String input) throws IOException {
            mPipeToInCall.write(input);
            mPipeToInCall.flush();
        }


        
Reads a string from the in-call app, blocking if there is no data available. Returns null if the RTT conversation has been terminated and there is no further data to read. 

This method is not thread-safe -- calling it from multiple threads simultaneously may
lead to interleaved text.
Returns:
A string containing text entered by the user, or null if the conversation has been terminated or if there was an error while reading./**
         * Reads a string from the in-call app, blocking if there is no data available. Returns
         * {@code null} if the RTT conversation has been terminated and there is no further data
         * to read.
         * <p>
         * This method is not thread-safe -- calling it from multiple threads simultaneously may
         * lead to interleaved text.
         *
         * @return A string containing text entered by the user, or {@code null} if the
         * conversation has been terminated or if there was an error while reading.
         */
        public String read() throws IOException {
            int numRead = mPipeFromInCall.read(mReadBuffer, 0, READ_BUFFER_SIZE);
            if (numRead < 0) {
                return null;
            }
            return new String(mReadBuffer, 0, numRead);
        }

        
Non-blocking version of read(). Returns null if there is nothing to be read. 
Returns:
A string containing text entered by the user, or null if the user has not entered any new text yet./**
         * Non-blocking version of {@link #read()}. Returns {@code null} if there is nothing to
         * be read.
         *
         * @return A string containing text entered by the user, or {@code null} if the user has
         * not entered any new text yet.
         */
        public String readImmediately() throws IOException {
            if (mFromInCallFileInputStream.available() > 0) {
                return read();
            } else {
                return null;
            }
        }

        
@hide
/** @hide */
        public ParcelFileDescriptor getFdFromInCall() {
            return mFdFromInCall;
        }

        
@hide
/** @hide */
        public ParcelFileDescriptor getFdToInCall() {
            return mFdToInCall;
        }
    }

    
Provides constants to represent the results of responses to session modify requests sent via Call.sendRttRequest() /**
     * Provides constants to represent the results of responses to session modify requests sent via
     * {@link Call#sendRttRequest()}
     */
    public static final class RttModifyStatus {
        private RttModifyStatus() {}
        
Session modify request was successful.
/**
         * Session modify request was successful.
         */
        public static final int SESSION_MODIFY_REQUEST_SUCCESS = 1;

        
Session modify request failed.
/**
         * Session modify request failed.
         */
        public static final int SESSION_MODIFY_REQUEST_FAIL = 2;

        
Session modify request ignored due to invalid parameters.
/**
         * Session modify request ignored due to invalid parameters.
         */
        public static final int SESSION_MODIFY_REQUEST_INVALID = 3;

        
Session modify request timed out.
/**
         * Session modify request timed out.
         */
        public static final int SESSION_MODIFY_REQUEST_TIMED_OUT = 4;

        
Session modify request rejected by remote user.
/**
         * Session modify request rejected by remote user.
         */
        public static final int SESSION_MODIFY_REQUEST_REJECTED_BY_REMOTE = 5;
    }

    
Provides a means of controlling the video session associated with a Connection. 
 Implementations create a custom subclass of VideoProvider and the ConnectionService creates an instance sets it on the Connection using Connection.setVideoProvider(VideoProvider). Any connection which supports video should set the VideoProvider. 
 The VideoProvider serves two primary purposes: it provides a means for Telecom and InCallService implementations to issue requests related to the video session; it provides a means for the ConnectionService to report events and information related to the video session to Telecom and the InCallService implementations. 
 InCallService implementations interact with the VideoProvider via VideoCall. /**
     * Provides a means of controlling the video session associated with a {@link Connection}.
     * <p>
     * Implementations create a custom subclass of {@link VideoProvider} and the
     * {@link ConnectionService} creates an instance sets it on the {@link Connection} using
     * {@link Connection#setVideoProvider(VideoProvider)}.  Any connection which supports video
     * should set the {@link VideoProvider}.
     * <p>
     * The {@link VideoProvider} serves two primary purposes: it provides a means for Telecom and
     * {@link InCallService} implementations to issue requests related to the video session;
     * it provides a means for the {@link ConnectionService} to report events and information
     * related to the video session to Telecom and the {@link InCallService} implementations.
     * <p>
     * {@link InCallService} implementations interact with the {@link VideoProvider} via
     * {@link android.telecom.InCallService.VideoCall}.
     */
    public static abstract class VideoProvider {
        
Video is not being received (no protocol pause was issued).
See Also:
handleCallSessionEvent(int)/**
         * Video is not being received (no protocol pause was issued).
         * @see #handleCallSessionEvent(int)
         */
        public static final int SESSION_EVENT_RX_PAUSE = 1;

        
Video reception has resumed after a SESSION_EVENT_RX_PAUSE. 
See Also:
handleCallSessionEvent(int)/**
         * Video reception has resumed after a {@link #SESSION_EVENT_RX_PAUSE}.
         * @see #handleCallSessionEvent(int)
         */
        public static final int SESSION_EVENT_RX_RESUME = 2;

        
Video transmission has begun. This occurs after a negotiated start of video transmission
when the underlying protocol has actually begun transmitting video to the remote party.
See Also:
handleCallSessionEvent(int)/**
         * Video transmission has begun. This occurs after a negotiated start of video transmission
         * when the underlying protocol has actually begun transmitting video to the remote party.
         * @see #handleCallSessionEvent(int)
         */
        public static final int SESSION_EVENT_TX_START = 3;

        
Video transmission has stopped. This occurs after a negotiated stop of video transmission
when the underlying protocol has actually stopped transmitting video to the remote party.
See Also:
handleCallSessionEvent(int)/**
         * Video transmission has stopped. This occurs after a negotiated stop of video transmission
         * when the underlying protocol has actually stopped transmitting video to the remote party.
         * @see #handleCallSessionEvent(int)
         */
        public static final int SESSION_EVENT_TX_STOP = 4;

        
A camera failure has occurred for the selected camera. The VideoProvider can use this as a cue to inform the user the camera is not available. 
See Also:
handleCallSessionEvent(int)/**
         * A camera failure has occurred for the selected camera.  The {@link VideoProvider} can use
         * this as a cue to inform the user the camera is not available.
         * @see #handleCallSessionEvent(int)
         */
        public static final int SESSION_EVENT_CAMERA_FAILURE = 5;

        
Issued after SESSION_EVENT_CAMERA_FAILURE when the camera is once again ready for operation. The VideoProvider can use this as a cue to inform the user that the camera has become available again. 
See Also:
handleCallSessionEvent(int)/**
         * Issued after {@link #SESSION_EVENT_CAMERA_FAILURE} when the camera is once again ready
         * for operation.  The {@link VideoProvider} can use this as a cue to inform the user that
         * the camera has become available again.
         * @see #handleCallSessionEvent(int)
         */
        public static final int SESSION_EVENT_CAMERA_READY = 6;

        
Session event raised by Telecom when VideoCall.setCamera(String) is called and the caller does not have the necessary CAMERA.CAMERA permission. 
See Also:
handleCallSessionEvent(int)/**
         * Session event raised by Telecom when
         * {@link android.telecom.InCallService.VideoCall#setCamera(String)} is called and the
         * caller does not have the necessary {@link android.Manifest.permission#CAMERA} permission.
         * @see #handleCallSessionEvent(int)
         */
        public static final int SESSION_EVENT_CAMERA_PERMISSION_ERROR = 7;

        
Session modify request was successful.
See Also:
receiveSessionModifyResponse(int, VideoProfile, VideoProfile)/**
         * Session modify request was successful.
         * @see #receiveSessionModifyResponse(int, VideoProfile, VideoProfile)
         */
        public static final int SESSION_MODIFY_REQUEST_SUCCESS = 1;

        
Session modify request failed.
See Also:
receiveSessionModifyResponse(int, VideoProfile, VideoProfile)/**
         * Session modify request failed.
         * @see #receiveSessionModifyResponse(int, VideoProfile, VideoProfile)
         */
        public static final int SESSION_MODIFY_REQUEST_FAIL = 2;

        
Session modify request ignored due to invalid parameters.
See Also:
receiveSessionModifyResponse(int, VideoProfile, VideoProfile)/**
         * Session modify request ignored due to invalid parameters.
         * @see #receiveSessionModifyResponse(int, VideoProfile, VideoProfile)
         */
        public static final int SESSION_MODIFY_REQUEST_INVALID = 3;

        
Session modify request timed out.
See Also:
receiveSessionModifyResponse(int, VideoProfile, VideoProfile)/**
         * Session modify request timed out.
         * @see #receiveSessionModifyResponse(int, VideoProfile, VideoProfile)
         */
        public static final int SESSION_MODIFY_REQUEST_TIMED_OUT = 4;

        
Session modify request rejected by remote user.
See Also:
receiveSessionModifyResponse(int, VideoProfile, VideoProfile)/**
         * Session modify request rejected by remote user.
         * @see #receiveSessionModifyResponse(int, VideoProfile, VideoProfile)
         */
        public static final int SESSION_MODIFY_REQUEST_REJECTED_BY_REMOTE = 5;

        private static final int MSG_ADD_VIDEO_CALLBACK = 1;
        private static final int MSG_SET_CAMERA = 2;
        private static final int MSG_SET_PREVIEW_SURFACE = 3;
        private static final int MSG_SET_DISPLAY_SURFACE = 4;
        private static final int MSG_SET_DEVICE_ORIENTATION = 5;
        private static final int MSG_SET_ZOOM = 6;
        private static final int MSG_SEND_SESSION_MODIFY_REQUEST = 7;
        private static final int MSG_SEND_SESSION_MODIFY_RESPONSE = 8;
        private static final int MSG_REQUEST_CAMERA_CAPABILITIES = 9;
        private static final int MSG_REQUEST_CONNECTION_DATA_USAGE = 10;
        private static final int MSG_SET_PAUSE_IMAGE = 11;
        private static final int MSG_REMOVE_VIDEO_CALLBACK = 12;

        private static final String SESSION_EVENT_RX_PAUSE_STR = "RX_PAUSE";
        private static final String SESSION_EVENT_RX_RESUME_STR = "RX_RESUME";
        private static final String SESSION_EVENT_TX_START_STR = "TX_START";
        private static final String SESSION_EVENT_TX_STOP_STR = "TX_STOP";
        private static final String SESSION_EVENT_CAMERA_FAILURE_STR = "CAMERA_FAIL";
        private static final String SESSION_EVENT_CAMERA_READY_STR = "CAMERA_READY";
        private static final String SESSION_EVENT_CAMERA_PERMISSION_ERROR_STR =
                "CAMERA_PERMISSION_ERROR";
        private static final String SESSION_EVENT_UNKNOWN_STR = "UNKNOWN";

        private VideoProvider.VideoProviderHandler mMessageHandler;
        private final VideoProvider.VideoProviderBinder mBinder;

        
Stores a list of the video callbacks, keyed by IBinder.
ConcurrentHashMap constructor params: 8 is initial table size, 0.9f is
load factor before resizing, 1 means we only expect a single thread to
access the map so make only a single shard
/**
         * Stores a list of the video callbacks, keyed by IBinder.
         *
         * ConcurrentHashMap constructor params: 8 is initial table size, 0.9f is
         * load factor before resizing, 1 means we only expect a single thread to
         * access the map so make only a single shard
         */
        private ConcurrentHashMap<IBinder, IVideoCallback> mVideoCallbacks =
                new ConcurrentHashMap<IBinder, IVideoCallback>(8, 0.9f, 1);

        
Default handler used to consolidate binder method calls onto a single thread.
/**
         * Default handler used to consolidate binder method calls onto a single thread.
         */
        private final class VideoProviderHandler extends Handler {
            public VideoProviderHandler() {
                super();
            }

            public VideoProviderHandler(Looper looper) {
                super(looper);
            }

            @Override
            public void handleMessage(Message msg) {
                switch (msg.what) {
                    case MSG_ADD_VIDEO_CALLBACK: {
                        IBinder binder = (IBinder) msg.obj;
                        IVideoCallback callback = IVideoCallback.Stub
                                .asInterface((IBinder) msg.obj);
                        if (callback == null) {
                            Log.w(this, "addVideoProvider - skipped; callback is null.");
                            break;
                        }

                        if (mVideoCallbacks.containsKey(binder)) {
                            Log.i(this, "addVideoProvider - skipped; already present.");
                            break;
                        }
                        mVideoCallbacks.put(binder, callback);
                        break;
                    }
                    case MSG_REMOVE_VIDEO_CALLBACK: {
                        IBinder binder = (IBinder) msg.obj;
                        IVideoCallback callback = IVideoCallback.Stub
                                .asInterface((IBinder) msg.obj);
                        if (!mVideoCallbacks.containsKey(binder)) {
                            Log.i(this, "removeVideoProvider - skipped; not present.");
                            break;
                        }
                        mVideoCallbacks.remove(binder);
                        break;
                    }
                    case MSG_SET_CAMERA:
                    {
                        SomeArgs args = (SomeArgs) msg.obj;
                        try {
                            onSetCamera((String) args.arg1);
                            onSetCamera((String) args.arg1, (String) args.arg2, args.argi1,
                                    args.argi2, args.argi3);
                        } finally {
                            args.recycle();
                        }
                    }
                    break;
                    case MSG_SET_PREVIEW_SURFACE:
                        onSetPreviewSurface((Surface) msg.obj);
                        break;
                    case MSG_SET_DISPLAY_SURFACE:
                        onSetDisplaySurface((Surface) msg.obj);
                        break;
                    case MSG_SET_DEVICE_ORIENTATION:
                        onSetDeviceOrientation(msg.arg1);
                        break;
                    case MSG_SET_ZOOM:
                        onSetZoom((Float) msg.obj);
                        break;
                    case MSG_SEND_SESSION_MODIFY_REQUEST: {
                        SomeArgs args = (SomeArgs) msg.obj;
                        try {
                            onSendSessionModifyRequest((VideoProfile) args.arg1,
                                    (VideoProfile) args.arg2);
                        } finally {
                            args.recycle();
                        }
                        break;
                    }
                    case MSG_SEND_SESSION_MODIFY_RESPONSE:
                        onSendSessionModifyResponse((VideoProfile) msg.obj);
                        break;
                    case MSG_REQUEST_CAMERA_CAPABILITIES:
                        onRequestCameraCapabilities();
                        break;
                    case MSG_REQUEST_CONNECTION_DATA_USAGE:
                        onRequestConnectionDataUsage();
                        break;
                    case MSG_SET_PAUSE_IMAGE:
                        onSetPauseImage((Uri) msg.obj);
                        break;
                    default:
                        break;
                }
            }
        }

        
IVideoProvider stub implementation.
/**
         * IVideoProvider stub implementation.
         */
        private final class VideoProviderBinder extends IVideoProvider.Stub {
            public void addVideoCallback(IBinder videoCallbackBinder) {
                mMessageHandler.obtainMessage(
                        MSG_ADD_VIDEO_CALLBACK, videoCallbackBinder).sendToTarget();
            }

            public void removeVideoCallback(IBinder videoCallbackBinder) {
                mMessageHandler.obtainMessage(
                        MSG_REMOVE_VIDEO_CALLBACK, videoCallbackBinder).sendToTarget();
            }

            public void setCamera(String cameraId, String callingPackageName,
                                  int targetSdkVersion) {

                SomeArgs args = SomeArgs.obtain();
                args.arg1 = cameraId;
                // Propagate the calling package; originally determined in
                // android.telecom.InCallService.VideoCall#setCamera(String) from the calling
                // process.
                args.arg2 = callingPackageName;
                // Pass along the uid and pid of the calling app; this gets lost when we put the
                // message onto the handler.  These are required for Telecom to perform a permission
                // check to see if the calling app is able to use the camera.
                args.argi1 = Binder.getCallingUid();
                args.argi2 = Binder.getCallingPid();
                // Pass along the target SDK version of the calling InCallService.  This is used to
                // maintain backwards compatibility of the API for older callers.
                args.argi3 = targetSdkVersion;
                mMessageHandler.obtainMessage(MSG_SET_CAMERA, args).sendToTarget();
            }

            public void setPreviewSurface(Surface surface) {
                mMessageHandler.obtainMessage(MSG_SET_PREVIEW_SURFACE, surface).sendToTarget();
            }

            public void setDisplaySurface(Surface surface) {
                mMessageHandler.obtainMessage(MSG_SET_DISPLAY_SURFACE, surface).sendToTarget();
            }

            public void setDeviceOrientation(int rotation) {
                mMessageHandler.obtainMessage(
                        MSG_SET_DEVICE_ORIENTATION, rotation, 0).sendToTarget();
            }

            public void setZoom(float value) {
                mMessageHandler.obtainMessage(MSG_SET_ZOOM, value).sendToTarget();
            }

            public void sendSessionModifyRequest(VideoProfile fromProfile, VideoProfile toProfile) {
                SomeArgs args = SomeArgs.obtain();
                args.arg1 = fromProfile;
                args.arg2 = toProfile;
                mMessageHandler.obtainMessage(MSG_SEND_SESSION_MODIFY_REQUEST, args).sendToTarget();
            }

            public void sendSessionModifyResponse(VideoProfile responseProfile) {
                mMessageHandler.obtainMessage(
                        MSG_SEND_SESSION_MODIFY_RESPONSE, responseProfile).sendToTarget();
            }

            public void requestCameraCapabilities() {
                mMessageHandler.obtainMessage(MSG_REQUEST_CAMERA_CAPABILITIES).sendToTarget();
            }

            public void requestCallDataUsage() {
                mMessageHandler.obtainMessage(MSG_REQUEST_CONNECTION_DATA_USAGE).sendToTarget();
            }

            public void setPauseImage(Uri uri) {
                mMessageHandler.obtainMessage(MSG_SET_PAUSE_IMAGE, uri).sendToTarget();
            }
        }

        public VideoProvider() {
            mBinder = new VideoProvider.VideoProviderBinder();
            mMessageHandler = new VideoProvider.VideoProviderHandler(Looper.getMainLooper());
        }

        
Creates an instance of the VideoProvider, specifying the looper to use. 
Params:
looper – The looper.
@hide
/**
         * Creates an instance of the {@link VideoProvider}, specifying the looper to use.
         *
         * @param looper The looper.
         * @hide
         */
        public VideoProvider(Looper looper) {
            mBinder = new VideoProvider.VideoProviderBinder();
            mMessageHandler = new VideoProvider.VideoProviderHandler(looper);
        }

        
Returns binder object which can be used across IPC methods.
@hide
/**
         * Returns binder object which can be used across IPC methods.
         * @hide
         */
        public final IVideoProvider getInterface() {
            return mBinder;
        }

        
Sets the camera to be used for the outgoing video.
 The VideoProvider should respond by communicating the capabilities of the chosen camera via changeCameraCapabilities(CameraCapabilities). 
 Sent from the InCallService via VideoCall.setCamera(String). 
Params:
cameraId – The id of the camera (use ids as reported by CameraManager.getCameraIdList())./**
         * Sets the camera to be used for the outgoing video.
         * <p>
         * The {@link VideoProvider} should respond by communicating the capabilities of the chosen
         * camera via
         * {@link VideoProvider#changeCameraCapabilities(VideoProfile.CameraCapabilities)}.
         * <p>
         * Sent from the {@link InCallService} via
         * {@link InCallService.VideoCall#setCamera(String)}.
         *
         * @param cameraId The id of the camera (use ids as reported by
         * {@link CameraManager#getCameraIdList()}).
         */
        public abstract void onSetCamera(String cameraId);

        
Sets the camera to be used for the outgoing video.
 The VideoProvider should respond by communicating the capabilities of the chosen camera via changeCameraCapabilities(CameraCapabilities). 

This prototype is used internally to ensure that the calling package name, UID and PID
are sent to Telecom so that can perform a camera permission check on the caller.
 Sent from the InCallService via VideoCall.setCamera(String). 
Params:
cameraId – The id of the camera (use ids as reported by CameraManager.getCameraIdList()).
callingPackageName – The AppOpps package name of the caller.
callingUid – The UID of the caller.
callingPid – The PID of the caller.
targetSdkVersion – The target SDK version of the caller.
@hide
/**
         * Sets the camera to be used for the outgoing video.
         * <p>
         * The {@link VideoProvider} should respond by communicating the capabilities of the chosen
         * camera via
         * {@link VideoProvider#changeCameraCapabilities(VideoProfile.CameraCapabilities)}.
         * <p>
         * This prototype is used internally to ensure that the calling package name, UID and PID
         * are sent to Telecom so that can perform a camera permission check on the caller.
         * <p>
         * Sent from the {@link InCallService} via
         * {@link InCallService.VideoCall#setCamera(String)}.
         *
         * @param cameraId The id of the camera (use ids as reported by
         * {@link CameraManager#getCameraIdList()}).
         * @param callingPackageName The AppOpps package name of the caller.
         * @param callingUid The UID of the caller.
         * @param callingPid The PID of the caller.
         * @param targetSdkVersion The target SDK version of the caller.
         * @hide
         */
        public void onSetCamera(String cameraId, String callingPackageName, int callingUid,
                int callingPid, int targetSdkVersion) {}

        
Sets the surface to be used for displaying a preview of what the user's camera is
currently capturing.  When video transmission is enabled, this is the video signal which
is sent to the remote device.
 Sent from the InCallService via VideoCall.setPreviewSurface(Surface). 
Params:
surface – The Surface./**
         * Sets the surface to be used for displaying a preview of what the user's camera is
         * currently capturing.  When video transmission is enabled, this is the video signal which
         * is sent to the remote device.
         * <p>
         * Sent from the {@link InCallService} via
         * {@link InCallService.VideoCall#setPreviewSurface(Surface)}.
         *
         * @param surface The {@link Surface}.
         */
        public abstract void onSetPreviewSurface(Surface surface);

        
Sets the surface to be used for displaying the video received from the remote device.
 Sent from the InCallService via VideoCall.setDisplaySurface(Surface). 
Params:
surface – The Surface./**
         * Sets the surface to be used for displaying the video received from the remote device.
         * <p>
         * Sent from the {@link InCallService} via
         * {@link InCallService.VideoCall#setDisplaySurface(Surface)}.
         *
         * @param surface The {@link Surface}.
         */
        public abstract void onSetDisplaySurface(Surface surface);

        
Sets the device orientation, in degrees.  Assumes that a standard portrait orientation of
the device is 0 degrees.
 Sent from the InCallService via VideoCall.setDeviceOrientation(int). 
Params:
rotation – The device orientation, in degrees./**
         * Sets the device orientation, in degrees.  Assumes that a standard portrait orientation of
         * the device is 0 degrees.
         * <p>
         * Sent from the {@link InCallService} via
         * {@link InCallService.VideoCall#setDeviceOrientation(int)}.
         *
         * @param rotation The device orientation, in degrees.
         */
        public abstract void onSetDeviceOrientation(int rotation);

        
Sets camera zoom ratio.
 Sent from the InCallService via VideoCall.setZoom(float). 
Params:
value – The camera zoom ratio./**
         * Sets camera zoom ratio.
         * <p>
         * Sent from the {@link InCallService} via {@link InCallService.VideoCall#setZoom(float)}.
         *
         * @param value The camera zoom ratio.
         */
        public abstract void onSetZoom(float value);

        
Issues a request to modify the properties of the current video session.
 Example scenarios include: requesting an audio-only call to be upgraded to a bi-directional video call, turning on or off the user's camera, sending a pause signal when the InCallService is no longer the foreground application. 
 If the VideoProvider determines a request to be invalid, it should call receiveSessionModifyResponse(int, VideoProfile, VideoProfile) to report the invalid request back to the InCallService. 
 Where a request requires confirmation from the user of the peer device, the VideoProvider must communicate the request to the peer device and handle the user's response. receiveSessionModifyResponse(int, VideoProfile, VideoProfile) is used to inform the InCallService of the result of the request. 
 Sent from the InCallService via VideoCall.sendSessionModifyRequest(VideoProfile). 
Params:
fromProfile – The video profile prior to the request.
toProfile – The video profile with the requested changes made./**
         * Issues a request to modify the properties of the current video session.
         * <p>
         * Example scenarios include: requesting an audio-only call to be upgraded to a
         * bi-directional video call, turning on or off the user's camera, sending a pause signal
         * when the {@link InCallService} is no longer the foreground application.
         * <p>
         * If the {@link VideoProvider} determines a request to be invalid, it should call
         * {@link #receiveSessionModifyResponse(int, VideoProfile, VideoProfile)} to report the
         * invalid request back to the {@link InCallService}.
         * <p>
         * Where a request requires confirmation from the user of the peer device, the
         * {@link VideoProvider} must communicate the request to the peer device and handle the
         * user's response.  {@link #receiveSessionModifyResponse(int, VideoProfile, VideoProfile)}
         * is used to inform the {@link InCallService} of the result of the request.
         * <p>
         * Sent from the {@link InCallService} via
         * {@link InCallService.VideoCall#sendSessionModifyRequest(VideoProfile)}.
         *
         * @param fromProfile The video profile prior to the request.
         * @param toProfile The video profile with the requested changes made.
         */
        public abstract void onSendSessionModifyRequest(VideoProfile fromProfile,
                VideoProfile toProfile);

        
Provides a response to a request to change the current video session properties.
 For example, if the peer requests and upgrade from an audio-only call to a bi-directional video call, could decline the request and keep the call as audio-only. In such a scenario, the responseProfile would have a video state of VideoProfile.STATE_AUDIO_ONLY. If the user had decided to accept the request, the video state would be VideoProfile.STATE_BIDIRECTIONAL. 
 Sent from the InCallService via VideoCall.sendSessionModifyResponse(VideoProfile) in response to a Callback.onSessionModifyRequestReceived(VideoProfile) callback. 
Params:
responseProfile – The response video profile./**
         * Provides a response to a request to change the current video session properties.
         * <p>
         * For example, if the peer requests and upgrade from an audio-only call to a bi-directional
         * video call, could decline the request and keep the call as audio-only.
         * In such a scenario, the {@code responseProfile} would have a video state of
         * {@link VideoProfile#STATE_AUDIO_ONLY}.  If the user had decided to accept the request,
         * the video state would be {@link VideoProfile#STATE_BIDIRECTIONAL}.
         * <p>
         * Sent from the {@link InCallService} via
         * {@link InCallService.VideoCall#sendSessionModifyResponse(VideoProfile)} in response to
         * a {@link InCallService.VideoCall.Callback#onSessionModifyRequestReceived(VideoProfile)}
         * callback.
         *
         * @param responseProfile The response video profile.
         */
        public abstract void onSendSessionModifyResponse(VideoProfile responseProfile);

        
Issues a request to the VideoProvider to retrieve the camera capabilities. 
 The VideoProvider should respond by communicating the capabilities of the chosen camera via changeCameraCapabilities(CameraCapabilities). 
 Sent from the InCallService via VideoCall.requestCameraCapabilities(). /**
         * Issues a request to the {@link VideoProvider} to retrieve the camera capabilities.
         * <p>
         * The {@link VideoProvider} should respond by communicating the capabilities of the chosen
         * camera via
         * {@link VideoProvider#changeCameraCapabilities(VideoProfile.CameraCapabilities)}.
         * <p>
         * Sent from the {@link InCallService} via
         * {@link InCallService.VideoCall#requestCameraCapabilities()}.
         */
        public abstract void onRequestCameraCapabilities();

        
Issues a request to the VideoProvider to retrieve the current data usage for the video component of the current Connection. 
 The VideoProvider should respond by communicating current data usage, in bytes, via setCallDataUsage(long). 
 Sent from the InCallService via VideoCall.requestCallDataUsage(). /**
         * Issues a request to the {@link VideoProvider} to retrieve the current data usage for the
         * video component of the current {@link Connection}.
         * <p>
         * The {@link VideoProvider} should respond by communicating current data usage, in bytes,
         * via {@link VideoProvider#setCallDataUsage(long)}.
         * <p>
         * Sent from the {@link InCallService} via
         * {@link InCallService.VideoCall#requestCallDataUsage()}.
         */
        public abstract void onRequestConnectionDataUsage();

        
Provides the VideoProvider with the Uri of an image to be displayed to the peer device when the video signal is paused. 
 Sent from the InCallService via VideoCall.setPauseImage(Uri). 
Params:
uri – URI of image to display./**
         * Provides the {@link VideoProvider} with the {@link Uri} of an image to be displayed to
         * the peer device when the video signal is paused.
         * <p>
         * Sent from the {@link InCallService} via
         * {@link InCallService.VideoCall#setPauseImage(Uri)}.
         *
         * @param uri URI of image to display.
         */
        public abstract void onSetPauseImage(Uri uri);

        
Used to inform listening InCallService implementations when the VideoProvider receives a session modification request. 
 Received by the InCallService via Callback.onSessionModifyRequestReceived(VideoProfile), 
Params:
videoProfile – The requested video profile.
See Also:
onSendSessionModifyRequest(VideoProfile, VideoProfile)/**
         * Used to inform listening {@link InCallService} implementations when the
         * {@link VideoProvider} receives a session modification request.
         * <p>
         * Received by the {@link InCallService} via
         * {@link InCallService.VideoCall.Callback#onSessionModifyRequestReceived(VideoProfile)},
         *
         * @param videoProfile The requested video profile.
         * @see #onSendSessionModifyRequest(VideoProfile, VideoProfile)
         */
        public void receiveSessionModifyRequest(VideoProfile videoProfile) {
            if (mVideoCallbacks != null) {
                for (IVideoCallback callback : mVideoCallbacks.values()) {
                    try {
                        callback.receiveSessionModifyRequest(videoProfile);
                    } catch (RemoteException ignored) {
                        Log.w(this, "receiveSessionModifyRequest callback failed", ignored);
                    }
                }
            }
        }

        
Used to inform listening InCallService implementations when the VideoProvider receives a response to a session modification request. 
 Received by the InCallService via Callback.onSessionModifyResponseReceived(int, VideoProfile, VideoProfile). 
Params:
status – Status of the session modify request. Valid values are SESSION_MODIFY_REQUEST_SUCCESS, SESSION_MODIFY_REQUEST_FAIL, SESSION_MODIFY_REQUEST_INVALID, SESSION_MODIFY_REQUEST_TIMED_OUT, SESSION_MODIFY_REQUEST_REJECTED_BY_REMOTE
requestedProfile – The original request which was sent to the peer device.
responseProfile – The actual profile changes agreed to by the peer device.
See Also:
onSendSessionModifyRequest(VideoProfile, VideoProfile)/**
         * Used to inform listening {@link InCallService} implementations when the
         * {@link VideoProvider} receives a response to a session modification request.
         * <p>
         * Received by the {@link InCallService} via
         * {@link InCallService.VideoCall.Callback#onSessionModifyResponseReceived(int,
         * VideoProfile, VideoProfile)}.
         *
         * @param status Status of the session modify request.  Valid values are
         *               {@link VideoProvider#SESSION_MODIFY_REQUEST_SUCCESS},
         *               {@link VideoProvider#SESSION_MODIFY_REQUEST_FAIL},
         *               {@link VideoProvider#SESSION_MODIFY_REQUEST_INVALID},
         *               {@link VideoProvider#SESSION_MODIFY_REQUEST_TIMED_OUT},
         *               {@link VideoProvider#SESSION_MODIFY_REQUEST_REJECTED_BY_REMOTE}
         * @param requestedProfile The original request which was sent to the peer device.
         * @param responseProfile The actual profile changes agreed to by the peer device.
         * @see #onSendSessionModifyRequest(VideoProfile, VideoProfile)
         */
        public void receiveSessionModifyResponse(int status,
                VideoProfile requestedProfile, VideoProfile responseProfile) {
            if (mVideoCallbacks != null) {
                for (IVideoCallback callback : mVideoCallbacks.values()) {
                    try {
                        callback.receiveSessionModifyResponse(status, requestedProfile,
                                responseProfile);
                    } catch (RemoteException ignored) {
                        Log.w(this, "receiveSessionModifyResponse callback failed", ignored);
                    }
                }
            }
        }

        
Used to inform listening InCallService implementations when the VideoProvider reports a call session event. 
 Received by the InCallService via Callback.onCallSessionEvent(int). 
Params:
event – The event. Valid values are: SESSION_EVENT_RX_PAUSE, SESSION_EVENT_RX_RESUME, SESSION_EVENT_TX_START, SESSION_EVENT_TX_STOP, SESSION_EVENT_CAMERA_FAILURE, SESSION_EVENT_CAMERA_READY, SESSION_EVENT_CAMERA_FAILURE./**
         * Used to inform listening {@link InCallService} implementations when the
         * {@link VideoProvider} reports a call session event.
         * <p>
         * Received by the {@link InCallService} via
         * {@link InCallService.VideoCall.Callback#onCallSessionEvent(int)}.
         *
         * @param event The event.  Valid values are: {@link VideoProvider#SESSION_EVENT_RX_PAUSE},
         *      {@link VideoProvider#SESSION_EVENT_RX_RESUME},
         *      {@link VideoProvider#SESSION_EVENT_TX_START},
         *      {@link VideoProvider#SESSION_EVENT_TX_STOP},
         *      {@link VideoProvider#SESSION_EVENT_CAMERA_FAILURE},
         *      {@link VideoProvider#SESSION_EVENT_CAMERA_READY},
         *      {@link VideoProvider#SESSION_EVENT_CAMERA_FAILURE}.
         */
        public void handleCallSessionEvent(int event) {
            if (mVideoCallbacks != null) {
                for (IVideoCallback callback : mVideoCallbacks.values()) {
                    try {
                        callback.handleCallSessionEvent(event);
                    } catch (RemoteException ignored) {
                        Log.w(this, "handleCallSessionEvent callback failed", ignored);
                    }
                }
            }
        }

        
Used to inform listening InCallService implementations when the dimensions of the peer's video have changed. 

This could occur if, for example, the peer rotates their device, changing the aspect
ratio of the video, or if the user switches between the back and front cameras.
 Received by the InCallService via Callback.onPeerDimensionsChanged(int, int). 
Params:
width –  The updated peer video width.
height – The updated peer video height./**
         * Used to inform listening {@link InCallService} implementations when the dimensions of the
         * peer's video have changed.
         * <p>
         * This could occur if, for example, the peer rotates their device, changing the aspect
         * ratio of the video, or if the user switches between the back and front cameras.
         * <p>
         * Received by the {@link InCallService} via
         * {@link InCallService.VideoCall.Callback#onPeerDimensionsChanged(int, int)}.
         *
         * @param width  The updated peer video width.
         * @param height The updated peer video height.
         */
        public void changePeerDimensions(int width, int height) {
            if (mVideoCallbacks != null) {
                for (IVideoCallback callback : mVideoCallbacks.values()) {
                    try {
                        callback.changePeerDimensions(width, height);
                    } catch (RemoteException ignored) {
                        Log.w(this, "changePeerDimensions callback failed", ignored);
                    }
                }
            }
        }

        
Used to inform listening InCallService implementations when the data usage of the video associated with the current Connection has changed. 
 This could be in response to a preview request via onRequestConnectionDataUsage(), or as a periodic update by the VideoProvider. Where periodic updates of data usage are provided, they should be provided at most for every 1 MB of data transferred and no more than once every 10 sec. 
 Received by the InCallService via Callback.onCallDataUsageChanged(long). 
Params:
dataUsage – The updated data usage (in bytes).  Reported as the cumulative bytes
                 used since the start of the call./**
         * Used to inform listening {@link InCallService} implementations when the data usage of the
         * video associated with the current {@link Connection} has changed.
         * <p>
         * This could be in response to a preview request via
         * {@link #onRequestConnectionDataUsage()}, or as a periodic update by the
         * {@link VideoProvider}.  Where periodic updates of data usage are provided, they should be
         * provided at most for every 1 MB of data transferred and no more than once every 10 sec.
         * <p>
         * Received by the {@link InCallService} via
         * {@link InCallService.VideoCall.Callback#onCallDataUsageChanged(long)}.
         *
         * @param dataUsage The updated data usage (in bytes).  Reported as the cumulative bytes
         *                  used since the start of the call.
         */
        public void setCallDataUsage(long dataUsage) {
            if (mVideoCallbacks != null) {
                for (IVideoCallback callback : mVideoCallbacks.values()) {
                    try {
                        callback.changeCallDataUsage(dataUsage);
                    } catch (RemoteException ignored) {
                        Log.w(this, "setCallDataUsage callback failed", ignored);
                    }
                }
            }
        }

        
Params:
dataUsage – The updated data usage (in byes).
See Also:
setCallDataUsage(long)
Deprecated:
- Use setCallDataUsage(long) instead.
@hide
/**
         * @see #setCallDataUsage(long)
         *
         * @param dataUsage The updated data usage (in byes).
         * @deprecated - Use {@link #setCallDataUsage(long)} instead.
         * @hide
         */
        public void changeCallDataUsage(long dataUsage) {
            setCallDataUsage(dataUsage);
        }

        
Used to inform listening InCallService implementations when the capabilities of the current camera have changed. 
 The VideoProvider should call this in response to onRequestCameraCapabilities(), or when the current camera is changed via onSetCamera(String). 
 Received by the InCallService via Callback.onCameraCapabilitiesChanged(CameraCapabilities). 
Params:
cameraCapabilities – The new camera capabilities./**
         * Used to inform listening {@link InCallService} implementations when the capabilities of
         * the current camera have changed.
         * <p>
         * The {@link VideoProvider} should call this in response to
         * {@link VideoProvider#onRequestCameraCapabilities()}, or when the current camera is
         * changed via {@link VideoProvider#onSetCamera(String)}.
         * <p>
         * Received by the {@link InCallService} via
         * {@link InCallService.VideoCall.Callback#onCameraCapabilitiesChanged(
         * VideoProfile.CameraCapabilities)}.
         *
         * @param cameraCapabilities The new camera capabilities.
         */
        public void changeCameraCapabilities(VideoProfile.CameraCapabilities cameraCapabilities) {
            if (mVideoCallbacks != null) {
                for (IVideoCallback callback : mVideoCallbacks.values()) {
                    try {
                        callback.changeCameraCapabilities(cameraCapabilities);
                    } catch (RemoteException ignored) {
                        Log.w(this, "changeCameraCapabilities callback failed", ignored);
                    }
                }
            }
        }

        
Used to inform listening InCallService implementations when the video quality of the call has changed. 
 Received by the InCallService via Callback.onVideoQualityChanged(int). 
Params:
videoQuality – The updated video quality. Valid values: VideoProfile.QUALITY_HIGH, VideoProfile.QUALITY_MEDIUM, VideoProfile.QUALITY_LOW, VideoProfile.QUALITY_DEFAULT./**
         * Used to inform listening {@link InCallService} implementations when the video quality
         * of the call has changed.
         * <p>
         * Received by the {@link InCallService} via
         * {@link InCallService.VideoCall.Callback#onVideoQualityChanged(int)}.
         *
         * @param videoQuality The updated video quality.  Valid values:
         *      {@link VideoProfile#QUALITY_HIGH},
         *      {@link VideoProfile#QUALITY_MEDIUM},
         *      {@link VideoProfile#QUALITY_LOW},
         *      {@link VideoProfile#QUALITY_DEFAULT}.
         */
        public void changeVideoQuality(int videoQuality) {
            if (mVideoCallbacks != null) {
                for (IVideoCallback callback : mVideoCallbacks.values()) {
                    try {
                        callback.changeVideoQuality(videoQuality);
                    } catch (RemoteException ignored) {
                        Log.w(this, "changeVideoQuality callback failed", ignored);
                    }
                }
            }
        }

        
Returns a string representation of a call session event.
Params:
event – A call session event passed to handleCallSessionEvent(int).
Returns:
String representation of the call session event.
@hide
/**
         * Returns a string representation of a call session event.
         *
         * @param event A call session event passed to {@link #handleCallSessionEvent(int)}.
         * @return String representation of the call session event.
         * @hide
         */
        public static String sessionEventToString(int event) {
            switch (event) {
                case SESSION_EVENT_CAMERA_FAILURE:
                    return SESSION_EVENT_CAMERA_FAILURE_STR;
                case SESSION_EVENT_CAMERA_READY:
                    return SESSION_EVENT_CAMERA_READY_STR;
                case SESSION_EVENT_RX_PAUSE:
                    return SESSION_EVENT_RX_PAUSE_STR;
                case SESSION_EVENT_RX_RESUME:
                    return SESSION_EVENT_RX_RESUME_STR;
                case SESSION_EVENT_TX_START:
                    return SESSION_EVENT_TX_START_STR;
                case SESSION_EVENT_TX_STOP:
                    return SESSION_EVENT_TX_STOP_STR;
                case SESSION_EVENT_CAMERA_PERMISSION_ERROR:
                    return SESSION_EVENT_CAMERA_PERMISSION_ERROR_STR;
                default:
                    return SESSION_EVENT_UNKNOWN_STR + " " + event;
            }
        }
    }

    private final Listener mConnectionDeathListener = new Listener() {
        @Override
        public void onDestroyed(Connection c) {
            if (mConferenceables.remove(c)) {
                fireOnConferenceableConnectionsChanged();
            }
        }
    };

    private final Conference.Listener mConferenceDeathListener = new Conference.Listener() {
        @Override
        public void onDestroyed(Conference c) {
            if (mConferenceables.remove(c)) {
                fireOnConferenceableConnectionsChanged();
            }
        }
    };

    
ConcurrentHashMap constructor params: 8 is initial table size, 0.9f is
load factor before resizing, 1 means we only expect a single thread to
access the map so make only a single shard
/**
     * ConcurrentHashMap constructor params: 8 is initial table size, 0.9f is
     * load factor before resizing, 1 means we only expect a single thread to
     * access the map so make only a single shard
     */
    private final Set<Listener> mListeners = Collections.newSetFromMap(
            new ConcurrentHashMap<Listener, Boolean>(8, 0.9f, 1));
    private final List<Conferenceable> mConferenceables = new ArrayList<>();
    private final List<Conferenceable> mUnmodifiableConferenceables =
            Collections.unmodifiableList(mConferenceables);

    // The internal telecom call ID associated with this connection.
    private String mTelecomCallId;
    // The PhoneAccountHandle associated with this connection.
    private PhoneAccountHandle mPhoneAccountHandle;
    private int mState = STATE_NEW;
    private CallAudioState mCallAudioState;
    private Uri mAddress;
    private int mAddressPresentation;
    private String mCallerDisplayName;
    private int mCallerDisplayNamePresentation;
    private boolean mRingbackRequested = false;
    private int mConnectionCapabilities;
    private int mConnectionProperties;
    private int mSupportedAudioRoutes = CallAudioState.ROUTE_ALL;
    private VideoProvider mVideoProvider;
    private boolean mAudioModeIsVoip;
    private long mConnectTimeMillis = Conference.CONNECT_TIME_NOT_SPECIFIED;
    private long mConnectElapsedTimeMillis = Conference.CONNECT_TIME_NOT_SPECIFIED;
    private StatusHints mStatusHints;
    private int mVideoState;
    private DisconnectCause mDisconnectCause;
    private Conference mConference;
    private ConnectionService mConnectionService;
    private Bundle mExtras;
    private final Object mExtrasLock = new Object();

    
Tracks the key set for the extras bundle provided on the last invocation of setExtras(Bundle). Used so that on subsequent invocations we can remove any extras keys which were set previously but are no longer present in the replacement Bundle. /**
     * Tracks the key set for the extras bundle provided on the last invocation of
     * {@link #setExtras(Bundle)}.  Used so that on subsequent invocations we can remove any extras
     * keys which were set previously but are no longer present in the replacement Bundle.
     */
    private Set<String> mPreviousExtraKeys;

    
Create a new Connection.
/**
     * Create a new Connection.
     */
    public Connection() {}

    
Returns the Telecom internal call ID associated with this connection.  Should only be used
for debugging and tracing purposes.
Returns:
The Telecom call ID.
@hide
/**
     * Returns the Telecom internal call ID associated with this connection.  Should only be used
     * for debugging and tracing purposes.
     *
     * @return The Telecom call ID.
     * @hide
     */
    public final String getTelecomCallId() {
        return mTelecomCallId;
    }

    
Returns:
The address (e.g., phone number) to which this Connection is currently communicating./**
     * @return The address (e.g., phone number) to which this Connection is currently communicating.
     */
    public final Uri getAddress() {
        return mAddress;
    }

    
Returns:
The presentation requirements for the address. See TelecomManager for valid values./**
     * @return The presentation requirements for the address.
     *         See {@link TelecomManager} for valid values.
     */
    public final int getAddressPresentation() {
        return mAddressPresentation;
    }

    
Returns:
The caller display name (CNAP)./**
     * @return The caller display name (CNAP).
     */
    public final String getCallerDisplayName() {
        return mCallerDisplayName;
    }

    
Returns:
The presentation requirements for the handle. See TelecomManager for valid values./**
     * @return The presentation requirements for the handle.
     *         See {@link TelecomManager} for valid values.
     */
    public final int getCallerDisplayNamePresentation() {
        return mCallerDisplayNamePresentation;
    }

    
Returns:
The state of this Connection./**
     * @return The state of this Connection.
     */
    public final int getState() {
        return mState;
    }

    
Returns the video state of the connection. Valid values: VideoProfile.STATE_AUDIO_ONLY, VideoProfile.STATE_BIDIRECTIONAL, VideoProfile.STATE_TX_ENABLED, VideoProfile.STATE_RX_ENABLED. 
Returns:
The video state of the connection.
@hide
/**
     * Returns the video state of the connection.
     * Valid values: {@link VideoProfile#STATE_AUDIO_ONLY},
     * {@link VideoProfile#STATE_BIDIRECTIONAL},
     * {@link VideoProfile#STATE_TX_ENABLED},
     * {@link VideoProfile#STATE_RX_ENABLED}.
     *
     * @return The video state of the connection.
     * @hide
     */
    public final int getVideoState() {
        return mVideoState;
    }

    
Returns:
The audio state of the connection, describing how its audio is currently being routed by the system. This is null if this Connection does not directly know about its audio state.
Deprecated:
Use getCallAudioState() instead.
@hide
/**
     * @return The audio state of the connection, describing how its audio is currently
     *         being routed by the system. This is {@code null} if this Connection
     *         does not directly know about its audio state.
     * @deprecated Use {@link #getCallAudioState()} instead.
     * @hide
     */
    @SystemApi
    @Deprecated
    public final AudioState getAudioState() {
        if (mCallAudioState == null) {
          return null;
        }
        return new AudioState(mCallAudioState);
    }

    
Returns:
The audio state of the connection, describing how its audio is currently being routed by the system. This is null if this Connection does not directly know about its audio state./**
     * @return The audio state of the connection, describing how its audio is currently
     *         being routed by the system. This is {@code null} if this Connection
     *         does not directly know about its audio state.
     */
    public final CallAudioState getCallAudioState() {
        return mCallAudioState;
    }

    
Returns:
The conference that this connection is a part of.  Null if it is not part of any
        conference./**
     * @return The conference that this connection is a part of.  Null if it is not part of any
     *         conference.
     */
    public final Conference getConference() {
        return mConference;
    }

    
Returns whether this connection is requesting that the system play a ringback tone
on its behalf.
/**
     * Returns whether this connection is requesting that the system play a ringback tone
     * on its behalf.
     */
    public final boolean isRingbackRequested() {
        return mRingbackRequested;
    }

    
Returns:
True if the connection's audio mode is VOIP./**
     * @return True if the connection's audio mode is VOIP.
     */
    public final boolean getAudioModeIsVoip() {
        return mAudioModeIsVoip;
    }

    
Retrieves the connection start time of the Connnection, if specified. A value of Conference.CONNECT_TIME_NOT_SPECIFIED indicates that Telecom should determine the start time of the conference. 
Returns:
The time at which the Connnection was connected.
@hide
/**
     * Retrieves the connection start time of the {@code Connnection}, if specified.  A value of
     * {@link Conference#CONNECT_TIME_NOT_SPECIFIED} indicates that Telecom should determine the
     * start time of the conference.
     *
     * @return The time at which the {@code Connnection} was connected.
     *
     * @hide
     */
    public final long getConnectTimeMillis() {
        return mConnectTimeMillis;
    }

    
Retrieves the connection start time of the Connection, if specified. A value of Conference.CONNECT_TIME_NOT_SPECIFIED indicates that Telecom should determine the start time of the conference. Based on the value of SystemClock.elapsedRealtime(), which ensures that wall-clock changes do not impact the call duration. 
Returns:
The time at which the Connection was connected.
@hide
/**
     * Retrieves the connection start time of the {@link Connection}, if specified.  A value of
     * {@link Conference#CONNECT_TIME_NOT_SPECIFIED} indicates that Telecom should determine the
     * start time of the conference.
     *
     * Based on the value of {@link SystemClock#elapsedRealtime()}, which ensures that wall-clock
     * changes do not impact the call duration.
     *
     * @return The time at which the {@link Connection} was connected.
     *
     * @hide
     */
    public final long getConnectElapsedTimeMillis() {
        return mConnectElapsedTimeMillis;
    }

    
Returns:
The status hints for this connection./**
     * @return The status hints for this connection.
     */
    public final StatusHints getStatusHints() {
        return mStatusHints;
    }

    
Returns the extras associated with this connection.
 Extras should be updated using putExtras(Bundle). 
 Telecom or an InCallService can also update the extras via Call.putExtras(Bundle), and Call.removeExtras(List<String>). 
 The connection is notified of changes to the extras made by Telecom or an InCallService by onExtrasChanged(Bundle). 
Returns:
The extras associated with this connection./**
     * Returns the extras associated with this connection.
     * <p>
     * Extras should be updated using {@link #putExtras(Bundle)}.
     * <p>
     * Telecom or an {@link InCallService} can also update the extras via
     * {@link android.telecom.Call#putExtras(Bundle)}, and
     * {@link Call#removeExtras(List)}.
     * <p>
     * The connection is notified of changes to the extras made by Telecom or an
     * {@link InCallService} by {@link #onExtrasChanged(Bundle)}.
     *
     * @return The extras associated with this connection.
     */
    public final Bundle getExtras() {
        Bundle extras = null;
        synchronized (mExtrasLock) {
            if (mExtras != null) {
                extras = new Bundle(mExtras);
            }
        }
        return extras;
    }

    
Assign a listener to be notified of state changes.
Params:
l – A listener.
Returns:
This Connection.
@hide
/**
     * Assign a listener to be notified of state changes.
     *
     * @param l A listener.
     * @return This Connection.
     *
     * @hide
     */
    public final Connection addConnectionListener(Listener l) {
        mListeners.add(l);
        return this;
    }

    
Remove a previously assigned listener that was being notified of state changes.
Params:
l – A Listener.
Returns:
This Connection.
@hide
/**
     * Remove a previously assigned listener that was being notified of state changes.
     *
     * @param l A Listener.
     * @return This Connection.
     *
     * @hide
     */
    public final Connection removeConnectionListener(Listener l) {
        if (l != null) {
            mListeners.remove(l);
        }
        return this;
    }

    
Returns:
The DisconnectCause for this connection./**
     * @return The {@link DisconnectCause} for this connection.
     */
    public final DisconnectCause getDisconnectCause() {
        return mDisconnectCause;
    }

    
Sets the telecom call ID associated with this Connection.  The Telecom Call ID should be used
ONLY for debugging purposes.
Params:
callId – The telecom call ID.
@hide
/**
     * Sets the telecom call ID associated with this Connection.  The Telecom Call ID should be used
     * ONLY for debugging purposes.
     *
     * @param callId The telecom call ID.
     * @hide
     */
    public void setTelecomCallId(String callId) {
        mTelecomCallId = callId;
    }

    
Inform this Connection that the state of its audio output has been changed externally.
Params:
state – The new audio state.
@hide
/**
     * Inform this Connection that the state of its audio output has been changed externally.
     *
     * @param state The new audio state.
     * @hide
     */
    final void setCallAudioState(CallAudioState state) {
        checkImmutable();
        Log.d(this, "setAudioState %s", state);
        mCallAudioState = state;
        onAudioStateChanged(getAudioState());
        onCallAudioStateChanged(state);
    }

    
Params:
state – An integer value of a STATE_* constant.
Returns:
A string representation of the value./**
     * @param state An integer value of a {@code STATE_*} constant.
     * @return A string representation of the value.
     */
    public static String stateToString(int state) {
        switch (state) {
            case STATE_INITIALIZING:
                return "INITIALIZING";
            case STATE_NEW:
                return "NEW";
            case STATE_RINGING:
                return "RINGING";
            case STATE_DIALING:
                return "DIALING";
            case STATE_PULLING_CALL:
                return "PULLING_CALL";
            case STATE_ACTIVE:
                return "ACTIVE";
            case STATE_HOLDING:
                return "HOLDING";
            case STATE_DISCONNECTED:
                return "DISCONNECTED";
            default:
                Log.wtf(Connection.class, "Unknown state %d", state);
                return "UNKNOWN";
        }
    }

    
Returns the connection's capabilities, as a bit mask of the CAPABILITY_* constants. /**
     * Returns the connection's capabilities, as a bit mask of the {@code CAPABILITY_*} constants.
     */
    public final int getConnectionCapabilities() {
        return mConnectionCapabilities;
    }

    
Returns the connection's properties, as a bit mask of the PROPERTY_* constants. /**
     * Returns the connection's properties, as a bit mask of the {@code PROPERTY_*} constants.
     */
    public final int getConnectionProperties() {
        return mConnectionProperties;
    }

    
Returns the connection's supported audio routes.
@hide
/**
     * Returns the connection's supported audio routes.
     *
     * @hide
     */
    public final int getSupportedAudioRoutes() {
        return mSupportedAudioRoutes;
    }

    
Sets the value of the getAddress() property. 
Params:
address – The new address.
presentation – The presentation requirements for the address. See TelecomManager for valid values./**
     * Sets the value of the {@link #getAddress()} property.
     *
     * @param address The new address.
     * @param presentation The presentation requirements for the address.
     *        See {@link TelecomManager} for valid values.
     */
    public final void setAddress(Uri address, int presentation) {
        checkImmutable();
        Log.d(this, "setAddress %s", address);
        mAddress = address;
        mAddressPresentation = presentation;
        for (Listener l : mListeners) {
            l.onAddressChanged(this, address, presentation);
        }
    }

    
Sets the caller display name (CNAP).
Params:
callerDisplayName – The new display name.
presentation – The presentation requirements for the handle. See TelecomManager for valid values./**
     * Sets the caller display name (CNAP).
     *
     * @param callerDisplayName The new display name.
     * @param presentation The presentation requirements for the handle.
     *        See {@link TelecomManager} for valid values.
     */
    public final void setCallerDisplayName(String callerDisplayName, int presentation) {
        checkImmutable();
        Log.d(this, "setCallerDisplayName %s", callerDisplayName);
        mCallerDisplayName = callerDisplayName;
        mCallerDisplayNamePresentation = presentation;
        for (Listener l : mListeners) {
            l.onCallerDisplayNameChanged(this, callerDisplayName, presentation);
        }
    }

    
Set the video state for the connection. Valid values: VideoProfile.STATE_AUDIO_ONLY, VideoProfile.STATE_BIDIRECTIONAL, VideoProfile.STATE_TX_ENABLED, VideoProfile.STATE_RX_ENABLED. 
Params:
videoState – The new video state./**
     * Set the video state for the connection.
     * Valid values: {@link VideoProfile#STATE_AUDIO_ONLY},
     * {@link VideoProfile#STATE_BIDIRECTIONAL},
     * {@link VideoProfile#STATE_TX_ENABLED},
     * {@link VideoProfile#STATE_RX_ENABLED}.
     *
     * @param videoState The new video state.
     */
    public final void setVideoState(int videoState) {
        checkImmutable();
        Log.d(this, "setVideoState %d", videoState);
        mVideoState = videoState;
        for (Listener l : mListeners) {
            l.onVideoStateChanged(this, mVideoState);
        }
    }

    
Sets state to active (e.g., an ongoing connection where two or more parties can actively
communicate).
/**
     * Sets state to active (e.g., an ongoing connection where two or more parties can actively
     * communicate).
     */
    public final void setActive() {
        checkImmutable();
        setRingbackRequested(false);
        setState(STATE_ACTIVE);
    }

    
Sets state to ringing (e.g., an inbound ringing connection).
/**
     * Sets state to ringing (e.g., an inbound ringing connection).
     */
    public final void setRinging() {
        checkImmutable();
        setState(STATE_RINGING);
    }

    
Sets state to initializing (this Connection is not yet ready to be used).
/**
     * Sets state to initializing (this Connection is not yet ready to be used).
     */
    public final void setInitializing() {
        checkImmutable();
        setState(STATE_INITIALIZING);
    }

    
Sets state to initialized (the Connection has been set up and is now ready to be used).
/**
     * Sets state to initialized (the Connection has been set up and is now ready to be used).
     */
    public final void setInitialized() {
        checkImmutable();
        setState(STATE_NEW);
    }

    
Sets state to dialing (e.g., dialing an outbound connection).
/**
     * Sets state to dialing (e.g., dialing an outbound connection).
     */
    public final void setDialing() {
        checkImmutable();
        setState(STATE_DIALING);
    }

    
Sets state to pulling (e.g. the connection is being pulled to the local device from another device). Only applicable for Connections with PROPERTY_IS_EXTERNAL_CALL and CAPABILITY_CAN_PULL_CALL. /**
     * Sets state to pulling (e.g. the connection is being pulled to the local device from another
     * device).  Only applicable for {@link Connection}s with
     * {@link Connection#PROPERTY_IS_EXTERNAL_CALL} and {@link Connection#CAPABILITY_CAN_PULL_CALL}.
     */
    public final void setPulling() {
        checkImmutable();
        setState(STATE_PULLING_CALL);
    }

    
Sets state to be on hold.
/**
     * Sets state to be on hold.
     */
    public final void setOnHold() {
        checkImmutable();
        setState(STATE_HOLDING);
    }

    
Sets the video connection provider.
Params:
videoProvider – The video provider./**
     * Sets the video connection provider.
     * @param videoProvider The video provider.
     */
    public final void setVideoProvider(VideoProvider videoProvider) {
        checkImmutable();
        mVideoProvider = videoProvider;
        for (Listener l : mListeners) {
            l.onVideoProviderChanged(this, videoProvider);
        }
    }

    public final VideoProvider getVideoProvider() {
        return mVideoProvider;
    }

    
Sets state to disconnected.
Params:
disconnectCause – The reason for the disconnection, as specified by DisconnectCause./**
     * Sets state to disconnected.
     *
     * @param disconnectCause The reason for the disconnection, as specified by
     *         {@link DisconnectCause}.
     */
    public final void setDisconnected(DisconnectCause disconnectCause) {
        checkImmutable();
        mDisconnectCause = disconnectCause;
        setState(STATE_DISCONNECTED);
        Log.d(this, "Disconnected with cause %s", disconnectCause);
        for (Listener l : mListeners) {
            l.onDisconnected(this, disconnectCause);
        }
    }

    
Informs listeners that this Connection is in a post-dial wait state. This is done when (a) the Connection is issuing a DTMF sequence; (b) it has encountered a "wait" character; and (c) it wishes to inform the In-Call app that it is waiting for the end-user to send an onPostDialContinue(boolean) signal. 
Params:
remaining – The DTMF character sequence remaining to be emitted once the onPostDialContinue(boolean) is received, including any "wait" characters that remaining sequence may contain./**
     * Informs listeners that this {@code Connection} is in a post-dial wait state. This is done
     * when (a) the {@code Connection} is issuing a DTMF sequence; (b) it has encountered a "wait"
     * character; and (c) it wishes to inform the In-Call app that it is waiting for the end-user
     * to send an {@link #onPostDialContinue(boolean)} signal.
     *
     * @param remaining The DTMF character sequence remaining to be emitted once the
     *         {@link #onPostDialContinue(boolean)} is received, including any "wait" characters
     *         that remaining sequence may contain.
     */
    public final void setPostDialWait(String remaining) {
        checkImmutable();
        for (Listener l : mListeners) {
            l.onPostDialWait(this, remaining);
        }
    }

    
Informs listeners that this Connection has processed a character in the post-dial started state. This is done when (a) the Connection is issuing a DTMF sequence; and (b) it wishes to signal Telecom to play the corresponding DTMF tone locally. 
Params:
nextChar – The DTMF character that was just processed by the Connection./**
     * Informs listeners that this {@code Connection} has processed a character in the post-dial
     * started state. This is done when (a) the {@code Connection} is issuing a DTMF sequence;
     * and (b) it wishes to signal Telecom to play the corresponding DTMF tone locally.
     *
     * @param nextChar The DTMF character that was just processed by the {@code Connection}.
     */
    public final void setNextPostDialChar(char nextChar) {
        checkImmutable();
        for (Listener l : mListeners) {
            l.onPostDialChar(this, nextChar);
        }
    }

    
Requests that the framework play a ringback tone. This is to be invoked by implementations
that do not play a ringback tone themselves in the connection's audio stream.
Params:
ringback – Whether the ringback tone is to be played./**
     * Requests that the framework play a ringback tone. This is to be invoked by implementations
     * that do not play a ringback tone themselves in the connection's audio stream.
     *
     * @param ringback Whether the ringback tone is to be played.
     */
    public final void setRingbackRequested(boolean ringback) {
        checkImmutable();
        if (mRingbackRequested != ringback) {
            mRingbackRequested = ringback;
            for (Listener l : mListeners) {
                l.onRingbackRequested(this, ringback);
            }
        }
    }

    
Sets the connection's capabilities as a bit mask of the CAPABILITY_* constants. 
Params:
connectionCapabilities – The new connection capabilities./**
     * Sets the connection's capabilities as a bit mask of the {@code CAPABILITY_*} constants.
     *
     * @param connectionCapabilities The new connection capabilities.
     */
    public final void setConnectionCapabilities(int connectionCapabilities) {
        checkImmutable();
        if (mConnectionCapabilities != connectionCapabilities) {
            mConnectionCapabilities = connectionCapabilities;
            for (Listener l : mListeners) {
                l.onConnectionCapabilitiesChanged(this, mConnectionCapabilities);
            }
        }
    }

    
Sets the connection's properties as a bit mask of the PROPERTY_* constants. 
Params:
connectionProperties – The new connection properties./**
     * Sets the connection's properties as a bit mask of the {@code PROPERTY_*} constants.
     *
     * @param connectionProperties The new connection properties.
     */
    public final void setConnectionProperties(int connectionProperties) {
        checkImmutable();
        if (mConnectionProperties != connectionProperties) {
            mConnectionProperties = connectionProperties;
            for (Listener l : mListeners) {
                l.onConnectionPropertiesChanged(this, mConnectionProperties);
            }
        }
    }

    
Sets the supported audio routes.
Params:
supportedAudioRoutes – the supported audio routes as a bitmask. See CallAudioState
@hide
/**
     * Sets the supported audio routes.
     *
     * @param supportedAudioRoutes the supported audio routes as a bitmask.
     *                             See {@link CallAudioState}
     * @hide
     */
    public final void setSupportedAudioRoutes(int supportedAudioRoutes) {
        if ((supportedAudioRoutes
                & (CallAudioState.ROUTE_EARPIECE | CallAudioState.ROUTE_SPEAKER)) == 0) {
            throw new IllegalArgumentException(
                    "supported audio routes must include either speaker or earpiece");
        }

        if (mSupportedAudioRoutes != supportedAudioRoutes) {
            mSupportedAudioRoutes = supportedAudioRoutes;
            for (Listener l : mListeners) {
                l.onSupportedAudioRoutesChanged(this, mSupportedAudioRoutes);
            }
        }
    }

    
Tears down the Connection object.
/**
     * Tears down the Connection object.
     */
    public final void destroy() {
        for (Listener l : mListeners) {
            l.onDestroyed(this);
        }
    }

    
Requests that the framework use VOIP audio mode for this connection.
Params:
isVoip – True if the audio mode is VOIP./**
     * Requests that the framework use VOIP audio mode for this connection.
     *
     * @param isVoip True if the audio mode is VOIP.
     */
    public final void setAudioModeIsVoip(boolean isVoip) {
        checkImmutable();
        mAudioModeIsVoip = isVoip;
        for (Listener l : mListeners) {
            l.onAudioModeIsVoipChanged(this, isVoip);
        }
    }

    
Sets the time at which a call became active on this Connection. This is set only
when a conference call becomes active on this connection.
Params:
connectTimeMillis – The connection time, in milliseconds. Should be set using a value obtained from System.currentTimeMillis().
@hide
/**
     * Sets the time at which a call became active on this Connection. This is set only
     * when a conference call becomes active on this connection.
     *
     * @param connectTimeMillis The connection time, in milliseconds.  Should be set using a value
     *                          obtained from {@link System#currentTimeMillis()}.
     *
     * @hide
     */
    public final void setConnectTimeMillis(long connectTimeMillis) {
        mConnectTimeMillis = connectTimeMillis;
    }

    
Sets the time at which a call became active on this Connection. This is set only
when a conference call becomes active on this connection.
Params:
connectElapsedTimeMillis – The connection time, in milliseconds. Stored in the format SystemClock.elapsedRealtime().
@hide
/**
     * Sets the time at which a call became active on this Connection. This is set only
     * when a conference call becomes active on this connection.
     *
     * @param connectElapsedTimeMillis The connection time, in milliseconds.  Stored in the format
     *                              {@link SystemClock#elapsedRealtime()}.
     *
     * @hide
     */
    public final void setConnectionStartElapsedRealTime(long connectElapsedTimeMillis) {
        mConnectElapsedTimeMillis = connectElapsedTimeMillis;
    }

    
Sets the label and icon status to display in the in-call UI.
Params:
statusHints – The status label and icon to set./**
     * Sets the label and icon status to display in the in-call UI.
     *
     * @param statusHints The status label and icon to set.
     */
    public final void setStatusHints(StatusHints statusHints) {
        checkImmutable();
        mStatusHints = statusHints;
        for (Listener l : mListeners) {
            l.onStatusHintsChanged(this, statusHints);
        }
    }

    
Sets the connections with which this connection can be conferenced.
Params:
conferenceableConnections – The set of connections this connection can conference with./**
     * Sets the connections with which this connection can be conferenced.
     *
     * @param conferenceableConnections The set of connections this connection can conference with.
     */
    public final void setConferenceableConnections(List<Connection> conferenceableConnections) {
        checkImmutable();
        clearConferenceableList();
        for (Connection c : conferenceableConnections) {
            // If statement checks for duplicates in input. It makes it N^2 but we're dealing with a
            // small amount of items here.
            if (!mConferenceables.contains(c)) {
                c.addConnectionListener(mConnectionDeathListener);
                mConferenceables.add(c);
            }
        }
        fireOnConferenceableConnectionsChanged();
    }

    
Similar to setConferenceableConnections(List<Connection>), sets a list of connections or conferences with which this connection can be conferenced. 
Params:
conferenceables – The conferenceables./**
     * Similar to {@link #setConferenceableConnections(java.util.List)}, sets a list of connections
     * or conferences with which this connection can be conferenced.
     *
     * @param conferenceables The conferenceables.
     */
    public final void setConferenceables(List<Conferenceable> conferenceables) {
        clearConferenceableList();
        for (Conferenceable c : conferenceables) {
            // If statement checks for duplicates in input. It makes it N^2 but we're dealing with a
            // small amount of items here.
            if (!mConferenceables.contains(c)) {
                if (c instanceof Connection) {
                    Connection connection = (Connection) c;
                    connection.addConnectionListener(mConnectionDeathListener);
                } else if (c instanceof Conference) {
                    Conference conference = (Conference) c;
                    conference.addListener(mConferenceDeathListener);
                }
                mConferenceables.add(c);
            }
        }
        fireOnConferenceableConnectionsChanged();
    }

    
Returns the connections or conferences with which this connection can be conferenced.
/**
     * Returns the connections or conferences with which this connection can be conferenced.
     */
    public final List<Conferenceable> getConferenceables() {
        return mUnmodifiableConferenceables;
    }

    
@hide
/**
     * @hide
     */
    public final void setConnectionService(ConnectionService connectionService) {
        checkImmutable();
        if (mConnectionService != null) {
            Log.e(this, new Exception(), "Trying to set ConnectionService on a connection " +
                    "which is already associated with another ConnectionService.");
        } else {
            mConnectionService = connectionService;
        }
    }

    
@hide
/**
     * @hide
     */
    public final void unsetConnectionService(ConnectionService connectionService) {
        if (mConnectionService != connectionService) {
            Log.e(this, new Exception(), "Trying to remove ConnectionService from a Connection " +
                    "that does not belong to the ConnectionService.");
        } else {
            mConnectionService = null;
        }
    }

    
@hide
/**
     * @hide
     */
    public final ConnectionService getConnectionService() {
        return mConnectionService;
    }

    
Sets the conference that this connection is a part of. This will fail if the connection is already part of a conference. resetConference to un-set the conference first. 
Params:
conference – The conference.
Returns:
true if the conference was successfully set.
@hide
/**
     * Sets the conference that this connection is a part of. This will fail if the connection is
     * already part of a conference. {@link #resetConference} to un-set the conference first.
     *
     * @param conference The conference.
     * @return {@code true} if the conference was successfully set.
     * @hide
     */
    public final boolean setConference(Conference conference) {
        checkImmutable();
        // We check to see if it is already part of another conference.
        if (mConference == null) {
            mConference = conference;
            if (mConnectionService != null && mConnectionService.containsConference(conference)) {
                fireConferenceChanged();
            }
            return true;
        }
        return false;
    }

    
Resets the conference that this connection is a part of.
@hide
/**
     * Resets the conference that this connection is a part of.
     * @hide
     */
    public final void resetConference() {
        if (mConference != null) {
            Log.d(this, "Conference reset");
            mConference = null;
            fireConferenceChanged();
        }
    }

    
Set some extras that can be associated with this Connection. 
 New or existing keys are replaced in the Connection extras. Keys which are no longer in the new extras, but were present the last time setExtras was called are removed. 
 Alternatively you may use the putExtras(Bundle), and removeExtras(String...) methods to modify the extras. 

No assumptions should be made as to how an In-Call UI or service will handle these extras.
Keys should be fully qualified (e.g., com.example.MY_EXTRA) to avoid conflicts.
Params:
extras – The extras associated with this Connection./**
     * Set some extras that can be associated with this {@code Connection}.
     * <p>
     * New or existing keys are replaced in the {@code Connection} extras.  Keys which are no longer
     * in the new extras, but were present the last time {@code setExtras} was called are removed.
     * <p>
     * Alternatively you may use the {@link #putExtras(Bundle)}, and
     * {@link #removeExtras(String...)} methods to modify the extras.
     * <p>
     * No assumptions should be made as to how an In-Call UI or service will handle these extras.
     * Keys should be fully qualified (e.g., com.example.MY_EXTRA) to avoid conflicts.
     *
     * @param extras The extras associated with this {@code Connection}.
     */
    public final void setExtras(@Nullable Bundle extras) {
        checkImmutable();

        // Add/replace any new or changed extras values.
        putExtras(extras);

        // If we have used "setExtras" in the past, compare the key set from the last invocation to
        // the current one and remove any keys that went away.
        if (mPreviousExtraKeys != null) {
            List<String> toRemove = new ArrayList<String>();
            for (String oldKey : mPreviousExtraKeys) {
                if (extras == null || !extras.containsKey(oldKey)) {
                    toRemove.add(oldKey);
                }
            }
            if (!toRemove.isEmpty()) {
                removeExtras(toRemove);
            }
        }

        // Track the keys the last time set called setExtras.  This way, the next time setExtras is
        // called we can see if the caller has removed any extras values.
        if (mPreviousExtraKeys == null) {
            mPreviousExtraKeys = new ArraySet<String>();
        }
        mPreviousExtraKeys.clear();
        if (extras != null) {
            mPreviousExtraKeys.addAll(extras.keySet());
        }
    }

    
Adds some extras to this Connection. Existing keys are replaced and new ones are added. 

No assumptions should be made as to how an In-Call UI or service will handle these extras.
Keys should be fully qualified (e.g., com.example.MY_EXTRA) to avoid conflicts.
Params:
extras – The extras to add./**
     * Adds some extras to this {@code Connection}.  Existing keys are replaced and new ones are
     * added.
     * <p>
     * No assumptions should be made as to how an In-Call UI or service will handle these extras.
     * Keys should be fully qualified (e.g., com.example.MY_EXTRA) to avoid conflicts.
     *
     * @param extras The extras to add.
     */
    public final void putExtras(@NonNull Bundle extras) {
        checkImmutable();
        if (extras == null) {
            return;
        }
        // Creating a duplicate bundle so we don't have to synchronize on mExtrasLock while calling
        // the listeners.
        Bundle listenerExtras;
        synchronized (mExtrasLock) {
            if (mExtras == null) {
                mExtras = new Bundle();
            }
            mExtras.putAll(extras);
            listenerExtras = new Bundle(mExtras);
        }
        for (Listener l : mListeners) {
            // Create a new clone of the extras for each listener so that they don't clobber
            // each other
            l.onExtrasChanged(this, new Bundle(listenerExtras));
        }
    }

    
Adds a boolean extra to this Connection. 
Params:
key – The extra key.
value – The value.
@hide
/**
     * Adds a boolean extra to this {@code Connection}.
     *
     * @param key The extra key.
     * @param value The value.
     * @hide
     */
    public final void putExtra(String key, boolean value) {
        Bundle newExtras = new Bundle();
        newExtras.putBoolean(key, value);
        putExtras(newExtras);
    }

    
Adds an integer extra to this Connection. 
Params:
key – The extra key.
value – The value.
@hide
/**
     * Adds an integer extra to this {@code Connection}.
     *
     * @param key The extra key.
     * @param value The value.
     * @hide
     */
    public final void putExtra(String key, int value) {
        Bundle newExtras = new Bundle();
        newExtras.putInt(key, value);
        putExtras(newExtras);
    }

    
Adds a string extra to this Connection. 
Params:
key – The extra key.
value – The value.
@hide
/**
     * Adds a string extra to this {@code Connection}.
     *
     * @param key The extra key.
     * @param value The value.
     * @hide
     */
    public final void putExtra(String key, String value) {
        Bundle newExtras = new Bundle();
        newExtras.putString(key, value);
        putExtras(newExtras);
    }

    
Removes extras from this Connection. 
Params:
keys – The keys of the extras to remove./**
     * Removes extras from this {@code Connection}.
     *
     * @param keys The keys of the extras to remove.
     */
    public final void removeExtras(List<String> keys) {
        synchronized (mExtrasLock) {
            if (mExtras != null) {
                for (String key : keys) {
                    mExtras.remove(key);
                }
            }
        }
        List<String> unmodifiableKeys = Collections.unmodifiableList(keys);
        for (Listener l : mListeners) {
            l.onExtrasRemoved(this, unmodifiableKeys);
        }
    }

    
Removes extras from this Connection. 
Params:
keys – The keys of the extras to remove./**
     * Removes extras from this {@code Connection}.
     *
     * @param keys The keys of the extras to remove.
     */
    public final void removeExtras(String ... keys) {
        removeExtras(Arrays.asList(keys));
    }

    
Sets the audio route (speaker, bluetooth, etc...). When this request is honored, there will be change to the getCallAudioState(). 
 Used by self-managed ConnectionServices which wish to change the audio route for a self-managed Connection (see PhoneAccount.CAPABILITY_SELF_MANAGED.) 
 See also InCallService.setAudioRoute(int). 
Params:
route – The audio route to use (one of CallAudioState.ROUTE_BLUETOOTH, CallAudioState.ROUTE_EARPIECE, CallAudioState.ROUTE_SPEAKER, or CallAudioState.ROUTE_WIRED_HEADSET)./**
     * Sets the audio route (speaker, bluetooth, etc...).  When this request is honored, there will
     * be change to the {@link #getCallAudioState()}.
     * <p>
     * Used by self-managed {@link ConnectionService}s which wish to change the audio route for a
     * self-managed {@link Connection} (see {@link PhoneAccount#CAPABILITY_SELF_MANAGED}.)
     * <p>
     * See also {@link InCallService#setAudioRoute(int)}.
     *
     * @param route The audio route to use (one of {@link CallAudioState#ROUTE_BLUETOOTH},
     *              {@link CallAudioState#ROUTE_EARPIECE}, {@link CallAudioState#ROUTE_SPEAKER}, or
     *              {@link CallAudioState#ROUTE_WIRED_HEADSET}).
     */
    public final void setAudioRoute(int route) {
        for (Listener l : mListeners) {
            l.onAudioRouteChanged(this, route, null);
        }
    }

    
Request audio routing to a specific bluetooth device. Calling this method may result in the device routing audio to a different bluetooth device than the one specified if the bluetooth stack is unable to route audio to the requested device. A list of available devices can be obtained via CallAudioState.getSupportedBluetoothDevices() 
 Used by self-managed ConnectionServices which wish to use bluetooth audio for a self-managed Connection (see PhoneAccount.CAPABILITY_SELF_MANAGED.) 
 See also InCallService.requestBluetoothAudio(BluetoothDevice) 
Params:
bluetoothDevice – The bluetooth device to connect to./**
     * Request audio routing to a specific bluetooth device. Calling this method may result in
     * the device routing audio to a different bluetooth device than the one specified if the
     * bluetooth stack is unable to route audio to the requested device.
     * A list of available devices can be obtained via
     * {@link CallAudioState#getSupportedBluetoothDevices()}
     *
     * <p>
     * Used by self-managed {@link ConnectionService}s which wish to use bluetooth audio for a
     * self-managed {@link Connection} (see {@link PhoneAccount#CAPABILITY_SELF_MANAGED}.)
     * <p>
     * See also {@link InCallService#requestBluetoothAudio(BluetoothDevice)}
     * @param bluetoothDevice The bluetooth device to connect to.
     */
    public void requestBluetoothAudio(@NonNull BluetoothDevice bluetoothDevice) {
        for (Listener l : mListeners) {
            l.onAudioRouteChanged(this, CallAudioState.ROUTE_BLUETOOTH,
                    bluetoothDevice.getAddress());
        }
    }

    
Informs listeners that a previously requested RTT session via ConnectionRequest.isRequestingRtt() or onStartRtt(RttTextStream) has succeeded. /**
     * Informs listeners that a previously requested RTT session via
     * {@link ConnectionRequest#isRequestingRtt()} or
     * {@link #onStartRtt(RttTextStream)} has succeeded.
     */
    public final void sendRttInitiationSuccess() {
        mListeners.forEach((l) -> l.onRttInitiationSuccess(Connection.this));
    }

    
Informs listeners that a previously requested RTT session via ConnectionRequest.isRequestingRtt() or onStartRtt(RttTextStream) has failed. 
Params:
reason – One of the reason codes defined in RttModifyStatus, with the exception of RttModifyStatus.SESSION_MODIFY_REQUEST_SUCCESS./**
     * Informs listeners that a previously requested RTT session via
     * {@link ConnectionRequest#isRequestingRtt()} or {@link #onStartRtt(RttTextStream)}
     * has failed.
     * @param reason One of the reason codes defined in {@link RttModifyStatus}, with the
     *               exception of {@link RttModifyStatus#SESSION_MODIFY_REQUEST_SUCCESS}.
     */
    public final void sendRttInitiationFailure(int reason) {
        mListeners.forEach((l) -> l.onRttInitiationFailure(Connection.this, reason));
    }

    
Informs listeners that a currently active RTT session has been terminated by the remote
side of the coll.
/**
     * Informs listeners that a currently active RTT session has been terminated by the remote
     * side of the coll.
     */
    public final void sendRttSessionRemotelyTerminated() {
        mListeners.forEach((l) -> l.onRttSessionRemotelyTerminated(Connection.this));
    }

    
Informs listeners that the remote side of the call has requested an upgrade to include an
RTT session in the call.
/**
     * Informs listeners that the remote side of the call has requested an upgrade to include an
     * RTT session in the call.
     */
    public final void sendRemoteRttRequest() {
        mListeners.forEach((l) -> l.onRemoteRttRequest(Connection.this));
    }

    
Notifies this Connection that the getAudioState() property has a new value. 
Params:
state – The new connection audio state.
Deprecated:
Use onCallAudioStateChanged(CallAudioState) instead.
@hide
/**
     * Notifies this Connection that the {@link #getAudioState()} property has a new value.
     *
     * @param state The new connection audio state.
     * @deprecated Use {@link #onCallAudioStateChanged(CallAudioState)} instead.
     * @hide
     */
    @SystemApi
    @Deprecated
    public void onAudioStateChanged(AudioState state) {}

    
Notifies this Connection that the getCallAudioState() property has a new value. 
Params:
state – The new connection audio state./**
     * Notifies this Connection that the {@link #getCallAudioState()} property has a new value.
     *
     * @param state The new connection audio state.
     */
    public void onCallAudioStateChanged(CallAudioState state) {}

    
Notifies this Connection of an internal state change. This method is called after the
state is changed.
Params:
state – The new state, one of the STATE_* constants./**
     * Notifies this Connection of an internal state change. This method is called after the
     * state is changed.
     *
     * @param state The new state, one of the {@code STATE_*} constants.
     */
    public void onStateChanged(int state) {}

    
Notifies this Connection of a request to play a DTMF tone.
Params:
c – A DTMF character./**
     * Notifies this Connection of a request to play a DTMF tone.
     *
     * @param c A DTMF character.
     */
    public void onPlayDtmfTone(char c) {}

    
Notifies this Connection of a request to stop any currently playing DTMF tones.
/**
     * Notifies this Connection of a request to stop any currently playing DTMF tones.
     */
    public void onStopDtmfTone() {}

    
Notifies this Connection of a request to disconnect.
/**
     * Notifies this Connection of a request to disconnect.
     */
    public void onDisconnect() {}

    
Notifies this Connection of a request to disconnect a participant of the conference managed
by the connection.
Params:
endpoint – the Uri of the participant to disconnect.
@hide
/**
     * Notifies this Connection of a request to disconnect a participant of the conference managed
     * by the connection.
     *
     * @param endpoint the {@link Uri} of the participant to disconnect.
     * @hide
     */
    public void onDisconnectConferenceParticipant(Uri endpoint) {}

    
Notifies this Connection of a request to separate from its parent conference.
/**
     * Notifies this Connection of a request to separate from its parent conference.
     */
    public void onSeparate() {}

    
Notifies this Connection of a request to abort.
/**
     * Notifies this Connection of a request to abort.
     */
    public void onAbort() {}

    
Notifies this Connection of a request to hold.
/**
     * Notifies this Connection of a request to hold.
     */
    public void onHold() {}

    
Notifies this Connection of a request to exit a hold state.
/**
     * Notifies this Connection of a request to exit a hold state.
     */
    public void onUnhold() {}

    
Notifies this Connection, which is in STATE_RINGING, of a request to accept. 
 For managed ConnectionServices, this will be called when the user answers a call via the default dialer's InCallService. 
 Although a self-managed ConnectionService provides its own incoming call UI, the Telecom framework may request that the call is answered in the following circumstances: 

    
The user chooses to answer an incoming call via a Bluetooth device.
    
A car mode InCallService is in use which has declared TelecomManager.METADATA_INCLUDE_SELF_MANAGED_CALLS in its manifest. Such an InCallService will be able to see calls from self-managed ConnectionServices, and will be able to display an incoming call UI on their behalf.

Params:
videoState – The video state in which to answer the connection./**
     * Notifies this Connection, which is in {@link #STATE_RINGING}, of
     * a request to accept.
     * <p>
     * For managed {@link ConnectionService}s, this will be called when the user answers a call via
     * the default dialer's {@link InCallService}.
     * <p>
     * Although a self-managed {@link ConnectionService} provides its own incoming call UI, the
     * Telecom framework may request that the call is answered in the following circumstances:
     * <ul>
     *     <li>The user chooses to answer an incoming call via a Bluetooth device.</li>
     *     <li>A car mode {@link InCallService} is in use which has declared
     *     {@link TelecomManager#METADATA_INCLUDE_SELF_MANAGED_CALLS} in its manifest.  Such an
     *     {@link InCallService} will be able to see calls from self-managed
     *     {@link ConnectionService}s, and will be able to display an incoming call UI on their
     *     behalf.</li>
     * </ul>
     * @param videoState The video state in which to answer the connection.
     */
    public void onAnswer(int videoState) {}

    
Notifies this Connection, which is in STATE_RINGING, of a request to accept. 
 For managed ConnectionServices, this will be called when the user answers a call via the default dialer's InCallService. 
 Although a self-managed ConnectionService provides its own incoming call UI, the Telecom framework may request that the call is answered in the following circumstances: 

    
The user chooses to answer an incoming call via a Bluetooth device.
    
A car mode InCallService is in use which has declared TelecomManager.METADATA_INCLUDE_SELF_MANAGED_CALLS in its manifest. Such an InCallService will be able to see calls from self-managed ConnectionServices, and will be able to display an incoming call UI on their behalf.

/**
     * Notifies this Connection, which is in {@link #STATE_RINGING}, of
     * a request to accept.
     * <p>
     * For managed {@link ConnectionService}s, this will be called when the user answers a call via
     * the default dialer's {@link InCallService}.
     * <p>
     * Although a self-managed {@link ConnectionService} provides its own incoming call UI, the
     * Telecom framework may request that the call is answered in the following circumstances:
     * <ul>
     *     <li>The user chooses to answer an incoming call via a Bluetooth device.</li>
     *     <li>A car mode {@link InCallService} is in use which has declared
     *     {@link TelecomManager#METADATA_INCLUDE_SELF_MANAGED_CALLS} in its manifest.  Such an
     *     {@link InCallService} will be able to see calls from self-managed
     *     {@link ConnectionService}s, and will be able to display an incoming call UI on their
     *     behalf.</li>
     * </ul>
     */
    public void onAnswer() {
        onAnswer(VideoProfile.STATE_AUDIO_ONLY);
    }

    
Notifies this Connection, which is in STATE_RINGING, of a request to deflect. /**
     * Notifies this Connection, which is in {@link #STATE_RINGING}, of
     * a request to deflect.
     */
    public void onDeflect(Uri address) {}

    
Notifies this Connection, which is in STATE_RINGING, of a request to reject. 
 For managed ConnectionServices, this will be called when the user rejects a call via the default dialer's InCallService. 
 Although a self-managed ConnectionService provides its own incoming call UI, the Telecom framework may request that the call is rejected in the following circumstances: 

    
The user chooses to reject an incoming call via a Bluetooth device.
    
A car mode InCallService is in use which has declared TelecomManager.METADATA_INCLUDE_SELF_MANAGED_CALLS in its manifest. Such an InCallService will be able to see calls from self-managed ConnectionServices, and will be able to display an incoming call UI on their behalf.

/**
     * Notifies this Connection, which is in {@link #STATE_RINGING}, of
     * a request to reject.
     * <p>
     * For managed {@link ConnectionService}s, this will be called when the user rejects a call via
     * the default dialer's {@link InCallService}.
     * <p>
     * Although a self-managed {@link ConnectionService} provides its own incoming call UI, the
     * Telecom framework may request that the call is rejected in the following circumstances:
     * <ul>
     *     <li>The user chooses to reject an incoming call via a Bluetooth device.</li>
     *     <li>A car mode {@link InCallService} is in use which has declared
     *     {@link TelecomManager#METADATA_INCLUDE_SELF_MANAGED_CALLS} in its manifest.  Such an
     *     {@link InCallService} will be able to see calls from self-managed
     *     {@link ConnectionService}s, and will be able to display an incoming call UI on their
     *     behalf.</li>
     * </ul>
     */
    public void onReject() {}

    
Notifies this Connection, which is in STATE_RINGING, of a request to reject with a message. /**
     * Notifies this Connection, which is in {@link #STATE_RINGING}, of
     * a request to reject with a message.
     */
    public void onReject(String replyMessage) {}

    
Notifies the Connection of a request to silence the ringer.
@hide
/**
     * Notifies the Connection of a request to silence the ringer.
     *
     * @hide
     */
    public void onSilence() {}

    
Notifies this Connection whether the user wishes to proceed with the post-dial DTMF codes.
/**
     * Notifies this Connection whether the user wishes to proceed with the post-dial DTMF codes.
     */
    public void onPostDialContinue(boolean proceed) {}

    
Notifies this Connection of a request to pull an external call to the local device.
 The InCallService issues a request to pull an external call to the local device via Call.pullExternalCall(). 
 For a Connection to be pulled, both the CAPABILITY_CAN_PULL_CALL capability and PROPERTY_IS_EXTERNAL_CALL property bits must be set. 
 For more information on external calls, see PROPERTY_IS_EXTERNAL_CALL. /**
     * Notifies this Connection of a request to pull an external call to the local device.
     * <p>
     * The {@link InCallService} issues a request to pull an external call to the local device via
     * {@link Call#pullExternalCall()}.
     * <p>
     * For a Connection to be pulled, both the {@link Connection#CAPABILITY_CAN_PULL_CALL}
     * capability and {@link Connection#PROPERTY_IS_EXTERNAL_CALL} property bits must be set.
     * <p>
     * For more information on external calls, see {@link Connection#PROPERTY_IS_EXTERNAL_CALL}.
     */
    public void onPullExternalCall() {}

    
Notifies this Connection of a Call event initiated from an InCallService. 
 The InCallService issues a Call event via Call.sendCallEvent(String, Bundle). 
 Where possible, the Connection should make an attempt to handle Call events which are part of the android.telecom.* namespace. The Connection should ignore any events it does not wish to handle. Unexpected events should be handled gracefully, as it is possible that a InCallService has defined its own Call events which a Connection is not aware of. 
 See also Call.sendCallEvent(String, Bundle). 
Params:
event – The call event.
extras – Extras associated with the call event./**
     * Notifies this Connection of a {@link Call} event initiated from an {@link InCallService}.
     * <p>
     * The {@link InCallService} issues a Call event via {@link Call#sendCallEvent(String, Bundle)}.
     * <p>
     * Where possible, the Connection should make an attempt to handle {@link Call} events which
     * are part of the {@code android.telecom.*} namespace.  The Connection should ignore any events
     * it does not wish to handle.  Unexpected events should be handled gracefully, as it is
     * possible that a {@link InCallService} has defined its own Call events which a Connection is
     * not aware of.
     * <p>
     * See also {@link Call#sendCallEvent(String, Bundle)}.
     *
     * @param event The call event.
     * @param extras Extras associated with the call event.
     */
    public void onCallEvent(String event, Bundle extras) {}

    
Notifies this Connection that a handover has completed. 
 A handover is initiated with Call.handoverTo(PhoneAccountHandle, int, Bundle) on the initiating side of the handover, and TelecomManager.acceptHandover(Uri, int, PhoneAccountHandle). /**
     * Notifies this {@link Connection} that a handover has completed.
     * <p>
     * A handover is initiated with {@link android.telecom.Call#handoverTo(PhoneAccountHandle, int,
     * Bundle)} on the initiating side of the handover, and
     * {@link TelecomManager#acceptHandover(Uri, int, PhoneAccountHandle)}.
     */
    public void onHandoverComplete() {}

    
Notifies this Connection of a change to the extras made outside the ConnectionService. 
 These extras changes can originate from Telecom itself, or from an InCallService via the Call.putExtras(Bundle) and Call.removeExtras(List<String>). 
Params:
extras – The new extras bundle./**
     * Notifies this {@link Connection} of a change to the extras made outside the
     * {@link ConnectionService}.
     * <p>
     * These extras changes can originate from Telecom itself, or from an {@link InCallService} via
     * the {@link android.telecom.Call#putExtras(Bundle)} and
     * {@link Call#removeExtras(List)}.
     *
     * @param extras The new extras bundle.
     */
    public void onExtrasChanged(Bundle extras) {}

    
Notifies this Connection that its ConnectionService is responsible for displaying its incoming call user interface for the Connection. 
 Will only be called for incoming calls added via a self-managed ConnectionService (see PhoneAccount.CAPABILITY_SELF_MANAGED), where the ConnectionService should show its own incoming call user interface. 
 Where there are ongoing calls in other self-managed ConnectionServices, or in a regular ConnectionService, and it is not possible to hold these other calls, the Telecom framework will display its own incoming call user interface to allow the user to choose whether to answer the new incoming call and disconnect other ongoing calls, or to reject the new incoming call. 
 You should trigger the display of the incoming call user interface for your application by showing a Notification with a full-screen Intent specified. For example: 

    // Create an intent which triggers your fullscreen incoming call user interface.
    Intent intent = new Intent(Intent.ACTION_MAIN, null);
    intent.setFlags(Intent.FLAG_ACTIVITY_NO_USER_ACTION | Intent.FLAG_ACTIVITY_NEW_TASK);
    intent.setClass(context, YourIncomingCallActivity.class);
    PendingIntent pendingIntent = PendingIntent.getActivity(context, 1, intent, 0);
    // Build the notification as an ongoing high priority item; this ensures it will show as
    // a heads up notification which slides down over top of the current content.
    final Notification.Builder builder = new Notification.Builder(context);
    builder.setOngoing(true);
    builder.setPriority(Notification.PRIORITY_HIGH);
    // Set notification content intent to take user to fullscreen UI if user taps on the
    // notification body.
    builder.setContentIntent(pendingIntent);
    // Set full screen intent to trigger display of the fullscreen UI when the notification
    // manager deems it appropriate.
    builder.setFullScreenIntent(pendingIntent, true);
    // Setup notification content.
    builder.setSmallIcon( yourIconResourceId );
    builder.setContentTitle("Your notification title");
    builder.setContentText("Your notification content.");
    // Use builder.addAction(..) to add buttons to answer or reject the call.
    NotificationManager notificationManager = mContext.getSystemService(
        NotificationManager.class);
    notificationManager.notify(YOUR_TAG, YOUR_ID, builder.build());

/**
     * Notifies this {@link Connection} that its {@link ConnectionService} is responsible for
     * displaying its incoming call user interface for the {@link Connection}.
     * <p>
     * Will only be called for incoming calls added via a self-managed {@link ConnectionService}
     * (see {@link PhoneAccount#CAPABILITY_SELF_MANAGED}), where the {@link ConnectionService}
     * should show its own incoming call user interface.
     * <p>
     * Where there are ongoing calls in other self-managed {@link ConnectionService}s, or in a
     * regular {@link ConnectionService}, and it is not possible to hold these other calls, the
     * Telecom framework will display its own incoming call user interface to allow the user to
     * choose whether to answer the new incoming call and disconnect other ongoing calls, or to
     * reject the new incoming call.
     * <p>
     * You should trigger the display of the incoming call user interface for your application by
     * showing a {@link Notification} with a full-screen {@link Intent} specified.
     * For example:
     * <pre><code>
     *     // Create an intent which triggers your fullscreen incoming call user interface.
     *     Intent intent = new Intent(Intent.ACTION_MAIN, null);
     *     intent.setFlags(Intent.FLAG_ACTIVITY_NO_USER_ACTION | Intent.FLAG_ACTIVITY_NEW_TASK);
     *     intent.setClass(context, YourIncomingCallActivity.class);
     *     PendingIntent pendingIntent = PendingIntent.getActivity(context, 1, intent, 0);
     *
     *     // Build the notification as an ongoing high priority item; this ensures it will show as
     *     // a heads up notification which slides down over top of the current content.
     *     final Notification.Builder builder = new Notification.Builder(context);
     *     builder.setOngoing(true);
     *     builder.setPriority(Notification.PRIORITY_HIGH);
     *
     *     // Set notification content intent to take user to fullscreen UI if user taps on the
     *     // notification body.
     *     builder.setContentIntent(pendingIntent);
     *     // Set full screen intent to trigger display of the fullscreen UI when the notification
     *     // manager deems it appropriate.
     *     builder.setFullScreenIntent(pendingIntent, true);
     *
     *     // Setup notification content.
     *     builder.setSmallIcon( yourIconResourceId );
     *     builder.setContentTitle("Your notification title");
     *     builder.setContentText("Your notification content.");
     *
     *     // Use builder.addAction(..) to add buttons to answer or reject the call.
     *
     *     NotificationManager notificationManager = mContext.getSystemService(
     *         NotificationManager.class);
     *     notificationManager.notify(YOUR_TAG, YOUR_ID, builder.build());
     * </code></pre>
     */
    public void onShowIncomingCallUi() {}

    
Notifies this Connection that the user has requested an RTT session. The connection service should call sendRttInitiationSuccess or sendRttInitiationFailure to inform Telecom of the success or failure of the request, respectively. 
Params:
rttTextStream – The object that should be used to send text to or receive text from
                     the in-call app./**
     * Notifies this {@link Connection} that the user has requested an RTT session.
     * The connection service should call {@link #sendRttInitiationSuccess} or
     * {@link #sendRttInitiationFailure} to inform Telecom of the success or failure of the
     * request, respectively.
     * @param rttTextStream The object that should be used to send text to or receive text from
     *                      the in-call app.
     */
    public void onStartRtt(@NonNull RttTextStream rttTextStream) {}

    
Notifies this Connection that it should terminate any existing RTT communication channel. No response to Telecom is needed for this method. /**
     * Notifies this {@link Connection} that it should terminate any existing RTT communication
     * channel. No response to Telecom is needed for this method.
     */
    public void onStopRtt() {}

    
Notifies this connection of a response to a previous remotely-initiated RTT upgrade request sent via sendRemoteRttRequest. Acceptance of the request is indicated by the supplied RttTextStream being non-null, and rejection is indicated by rttTextStream being null 
Params:
rttTextStream – The object that should be used to send text to or receive text from
                     the in-call app./**
     * Notifies this connection of a response to a previous remotely-initiated RTT upgrade
     * request sent via {@link #sendRemoteRttRequest}. Acceptance of the request is
     * indicated by the supplied {@link RttTextStream} being non-null, and rejection is
     * indicated by {@code rttTextStream} being {@code null}
     * @param rttTextStream The object that should be used to send text to or receive text from
     *                      the in-call app.
     */
    public void handleRttUpgradeResponse(@Nullable RttTextStream rttTextStream) {}

    static String toLogSafePhoneNumber(String number) {
        // For unknown number, log empty string.
        if (number == null) {
            return "";
        }

        if (PII_DEBUG) {
            // When PII_DEBUG is true we emit PII.
            return number;
        }

        // Do exactly same thing as Uri#toSafeString() does, which will enable us to compare
        // sanitized phone numbers.
        StringBuilder builder = new StringBuilder();
        for (int i = 0; i < number.length(); i++) {
            char c = number.charAt(i);
            if (c == '-' || c == '@' || c == '.') {
                builder.append(c);
            } else {
                builder.append('x');
            }
        }
        return builder.toString();
    }

    private void setState(int state) {
        checkImmutable();
        if (mState == STATE_DISCONNECTED && mState != state) {
            Log.d(this, "Connection already DISCONNECTED; cannot transition out of this state.");
            return;
        }
        if (mState != state) {
            Log.d(this, "setState: %s", stateToString(state));
            mState = state;
            onStateChanged(state);
            for (Listener l : mListeners) {
                l.onStateChanged(this, state);
            }
        }
    }

    private static class FailureSignalingConnection extends Connection {
        private boolean mImmutable = false;
        public FailureSignalingConnection(DisconnectCause disconnectCause) {
            setDisconnected(disconnectCause);
            mImmutable = true;
        }

        public void checkImmutable() {
            if (mImmutable) {
                throw new UnsupportedOperationException("Connection is immutable");
            }
        }
    }

    
Return a Connection which represents a failed connection attempt. The returned Connection will have a DisconnectCause and as specified, and a getState() of STATE_DISCONNECTED. 
 The returned Connection can be assumed to destroy() itself when appropriate, so users of this method need not maintain a reference to its return value to destroy it. 
Params:
disconnectCause – The disconnect cause, ({@see android.telecomm.DisconnectCause}).
Returns:
A Connection which indicates failure./**
     * Return a {@code Connection} which represents a failed connection attempt. The returned
     * {@code Connection} will have a {@link android.telecom.DisconnectCause} and as specified,
     * and a {@link #getState()} of {@link #STATE_DISCONNECTED}.
     * <p>
     * The returned {@code Connection} can be assumed to {@link #destroy()} itself when appropriate,
     * so users of this method need not maintain a reference to its return value to destroy it.
     *
     * @param disconnectCause The disconnect cause, ({@see android.telecomm.DisconnectCause}).
     * @return A {@code Connection} which indicates failure.
     */
    public static Connection createFailedConnection(DisconnectCause disconnectCause) {
        return new FailureSignalingConnection(disconnectCause);
    }

    
Override to throw an UnsupportedOperationException if this Connection is not intended to be mutated, e.g., if it is a marker for failure. Only for framework use; this should never be un-@hide-den. 
@hide
/**
     * Override to throw an {@link UnsupportedOperationException} if this {@code Connection} is
     * not intended to be mutated, e.g., if it is a marker for failure. Only for framework use;
     * this should never be un-@hide-den.
     *
     * @hide
     */
    public void checkImmutable() {}

    
Return a Connection which represents a canceled connection attempt. The returned Connection will have state STATE_DISCONNECTED, and cannot be moved out of that state. This connection should not be used for anything, and no other Connections should be attempted. 

so users of this method need not maintain a reference to its return value to destroy it.
Returns:
A Connection which indicates that the underlying connection should be canceled./**
     * Return a {@code Connection} which represents a canceled connection attempt. The returned
     * {@code Connection} will have state {@link #STATE_DISCONNECTED}, and cannot be moved out of
     * that state. This connection should not be used for anything, and no other
     * {@code Connection}s should be attempted.
     * <p>
     * so users of this method need not maintain a reference to its return value to destroy it.
     *
     * @return A {@code Connection} which indicates that the underlying connection should
     * be canceled.
     */
    public static Connection createCanceledConnection() {
        return new FailureSignalingConnection(new DisconnectCause(DisconnectCause.CANCELED));
    }

    private final void fireOnConferenceableConnectionsChanged() {
        for (Listener l : mListeners) {
            l.onConferenceablesChanged(this, getConferenceables());
        }
    }

    private final void fireConferenceChanged() {
        for (Listener l : mListeners) {
            l.onConferenceChanged(this, mConference);
        }
    }

    private final void clearConferenceableList() {
        for (Conferenceable c : mConferenceables) {
            if (c instanceof Connection) {
                Connection connection = (Connection) c;
                connection.removeConnectionListener(mConnectionDeathListener);
            } else if (c instanceof Conference) {
                Conference conference = (Conference) c;
                conference.removeListener(mConferenceDeathListener);
            }
        }
        mConferenceables.clear();
    }

    
Handles a change to extras received from Telecom.
Params:
extras – The new extras.
@hide
/**
     * Handles a change to extras received from Telecom.
     *
     * @param extras The new extras.
     * @hide
     */
    final void handleExtrasChanged(Bundle extras) {
        Bundle b = null;
        synchronized (mExtrasLock) {
            mExtras = extras;
            if (mExtras != null) {
                b = new Bundle(mExtras);
            }
        }
        onExtrasChanged(b);
    }

    
Notifies listeners that the merge request failed.
@hide
/**
     * Notifies listeners that the merge request failed.
     *
     * @hide
     */
    protected final void notifyConferenceMergeFailed() {
        for (Listener l : mListeners) {
            l.onConferenceMergeFailed(this);
        }
    }

    
Notifies listeners of a change to conference participant(s).
Params:
conferenceParticipants – The participants.
@hide
/**
     * Notifies listeners of a change to conference participant(s).
     *
     * @param conferenceParticipants The participants.
     * @hide
     */
    protected final void updateConferenceParticipants(
            List<ConferenceParticipant> conferenceParticipants) {
        for (Listener l : mListeners) {
            l.onConferenceParticipantsChanged(this, conferenceParticipants);
        }
    }

    
Notifies listeners that a conference call has been started.
@hide
/**
     * Notifies listeners that a conference call has been started.
     * @hide
     */
    protected void notifyConferenceStarted() {
        for (Listener l : mListeners) {
            l.onConferenceStarted();
        }
    }

    
Notifies listeners when a change has occurred to the Connection which impacts its ability to
be a part of a conference call.
Params:
isConferenceSupported – true if the connection supports being part of a conference call, false otherwise.
@hide
/**
     * Notifies listeners when a change has occurred to the Connection which impacts its ability to
     * be a part of a conference call.
     * @param isConferenceSupported {@code true} if the connection supports being part of a
     *      conference call, {@code false} otherwise.
     * @hide
     */
    protected void notifyConferenceSupportedChanged(boolean isConferenceSupported) {
        for (Listener l : mListeners) {
            l.onConferenceSupportedChanged(this, isConferenceSupported);
        }
    }

    
Notifies listeners when phone account is changed. For example, when the PhoneAccount is
changed due to an emergency call being redialed.
Params:
pHandle – The new PhoneAccountHandle for this connection.
@hide
/**
     * Notifies listeners when phone account is changed. For example, when the PhoneAccount is
     * changed due to an emergency call being redialed.
     * @param pHandle The new PhoneAccountHandle for this connection.
     * @hide
     */
    public void notifyPhoneAccountChanged(PhoneAccountHandle pHandle) {
        for (Listener l : mListeners) {
            l.onPhoneAccountChanged(this, pHandle);
        }
    }

    
Sets the PhoneAccountHandle associated with this connection. 
@hide
/**
     * Sets the {@link PhoneAccountHandle} associated with this connection.
     *
     * @hide
     */
    public void setPhoneAccountHandle(PhoneAccountHandle phoneAccountHandle) {
        if (mPhoneAccountHandle != phoneAccountHandle) {
            mPhoneAccountHandle = phoneAccountHandle;
            notifyPhoneAccountChanged(phoneAccountHandle);
        }
    }

    
Returns the PhoneAccountHandle associated with this connection. 
@hide
/**
     * Returns the {@link PhoneAccountHandle} associated with this connection.
     *
     * @hide
     */
    public PhoneAccountHandle getPhoneAccountHandle() {
        return mPhoneAccountHandle;
    }

    
Sends an event associated with this Connection with associated event extras to the InCallService. 
 Connection events are used to communicate point in time information from a ConnectionService to a InCallService implementations. An example of a custom connection event includes notifying the UI when a WIFI call has been handed over to LTE, which the InCall UI might use to inform the user that billing charges may apply. The Android Telephony framework will send the EVENT_CALL_MERGE_FAILED connection event when a call to Call.mergeConference() has failed to complete successfully. A connection event could also be used to trigger UI in the InCallService which prompts the user to make a choice (e.g. whether they want to incur roaming costs for making a call), which is communicated back via Call.sendCallEvent(String, Bundle). 
 Events are exposed to InCallService implementations via Callback.onConnectionEvent(Call, String, Bundle). 
 No assumptions should be made as to how an In-Call UI or service will handle these events. The ConnectionService must assume that the In-Call UI could even chose to ignore some events altogether. 
 Events should be fully qualified (e.g. com.example.event.MY_EVENT) to avoid conflicts between ConnectionService implementations. Further, custom ConnectionService implementations shall not re-purpose events in the android.* namespace, nor shall they define new event types in this namespace. When defining a custom event type, ensure the contents of the extras Bundle is clearly defined. Extra keys for this bundle should be named similar to the event type (e.g. com.example.extra.MY_EXTRA). 
 When defining events and the associated extras, it is important to keep their behavior consistent when the associated ConnectionService is updated. Support for deprecated events/extras should me maintained to ensure backwards compatibility with older InCallService implementations which were built to support the older behavior. 
Params:
event – The connection event.
extras – Optional bundle containing extra information associated with the event./**
     * Sends an event associated with this {@code Connection} with associated event extras to the
     * {@link InCallService}.
     * <p>
     * Connection events are used to communicate point in time information from a
     * {@link ConnectionService} to a {@link InCallService} implementations.  An example of a
     * custom connection event includes notifying the UI when a WIFI call has been handed over to
     * LTE, which the InCall UI might use to inform the user that billing charges may apply.  The
     * Android Telephony framework will send the {@link #EVENT_CALL_MERGE_FAILED} connection event
     * when a call to {@link Call#mergeConference()} has failed to complete successfully.  A
     * connection event could also be used to trigger UI in the {@link InCallService} which prompts
     * the user to make a choice (e.g. whether they want to incur roaming costs for making a call),
     * which is communicated back via {@link Call#sendCallEvent(String, Bundle)}.
     * <p>
     * Events are exposed to {@link InCallService} implementations via
     * {@link Call.Callback#onConnectionEvent(Call, String, Bundle)}.
     * <p>
     * No assumptions should be made as to how an In-Call UI or service will handle these events.
     * The {@link ConnectionService} must assume that the In-Call UI could even chose to ignore
     * some events altogether.
     * <p>
     * Events should be fully qualified (e.g. {@code com.example.event.MY_EVENT}) to avoid
     * conflicts between {@link ConnectionService} implementations.  Further, custom
     * {@link ConnectionService} implementations shall not re-purpose events in the
     * {@code android.*} namespace, nor shall they define new event types in this namespace.  When
     * defining a custom event type, ensure the contents of the extras {@link Bundle} is clearly
     * defined.  Extra keys for this bundle should be named similar to the event type (e.g.
     * {@code com.example.extra.MY_EXTRA}).
     * <p>
     *  When defining events and the associated extras, it is important to keep their behavior
     * consistent when the associated {@link ConnectionService} is updated.  Support for deprecated
     * events/extras should me maintained to ensure backwards compatibility with older
     * {@link InCallService} implementations which were built to support the older behavior.
     *
     * @param event The connection event.
     * @param extras Optional bundle containing extra information associated with the event.
     */
    public void sendConnectionEvent(String event, Bundle extras) {
        for (Listener l : mListeners) {
            l.onConnectionEvent(this, event, extras);
        }
    }
}