https://openjdk.java.net/ 
/*
 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * questions.
 */
package java.beans;

import java.io.Serializable;
import java.io.ObjectStreamField;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import java.util.Hashtable;
import java.util.Map.Entry;


This is a utility class that can be used by beans that support constrained properties. It manages a list of listeners and dispatches PropertyChangeEvents to them. You can use an instance of this class as a member field of your bean and delegate these types of work to it. The VetoableChangeListener can be registered for all properties or for a property specified by name. 
 Here is an example of VetoableChangeSupport usage that follows the rules and recommendations laid out in the JavaBeans™ specification: 

public class MyBean {
    private final VetoableChangeSupport vcs = new VetoableChangeSupport(this);
    public void addVetoableChangeListener(VetoableChangeListener listener) {
        this.vcs.addVetoableChangeListener(listener);
    }
    public void removeVetoableChangeListener(VetoableChangeListener listener) {
        this.vcs.removeVetoableChangeListener(listener);
    }
    private String value;
    public String getValue() {
        return this.value;
    }
    public void setValue(String newValue) throws PropertyVetoException {
        String oldValue = this.value;
        this.vcs.fireVetoableChange("value", oldValue, newValue);
        this.value = newValue;
    }
    [...]
 }



 A VetoableChangeSupport instance is thread-safe. 

This class is serializable.  When it is serialized it will save
(and restore) any listeners that are themselves serializable.  Any
non-serializable listeners will be skipped during serialization.

See Also:
Since:1.1
/**
 * This is a utility class that can be used by beans that support constrained
 * properties.  It manages a list of listeners and dispatches
 * {@link PropertyChangeEvent}s to them.  You can use an instance of this class
 * as a member field of your bean and delegate these types of work to it.
 * The {@link VetoableChangeListener} can be registered for all properties
 * or for a property specified by name.
 * <p>
 * Here is an example of {@code VetoableChangeSupport} usage that follows
 * the rules and recommendations laid out in the JavaBeans&trade; specification:
 * <pre>{@code
 * public class MyBean {
 *     private final VetoableChangeSupport vcs = new VetoableChangeSupport(this);
 *
 *     public void addVetoableChangeListener(VetoableChangeListener listener) {
 *         this.vcs.addVetoableChangeListener(listener);
 *     }
 *
 *     public void removeVetoableChangeListener(VetoableChangeListener listener) {
 *         this.vcs.removeVetoableChangeListener(listener);
 *     }
 *
 *     private String value;
 *
 *     public String getValue() {
 *         return this.value;
 *     }
 *
 *     public void setValue(String newValue) throws PropertyVetoException {
 *         String oldValue = this.value;
 *         this.vcs.fireVetoableChange("value", oldValue, newValue);
 *         this.value = newValue;
 *     }
 *
 *     [...]
 * }
 * }</pre>
 * <p>
 * A {@code VetoableChangeSupport} instance is thread-safe.
 * <p>
 * This class is serializable.  When it is serialized it will save
 * (and restore) any listeners that are themselves serializable.  Any
 * non-serializable listeners will be skipped during serialization.
 *
 * @see PropertyChangeSupport
 * @since 1.1
 */
public class VetoableChangeSupport implements Serializable {
    private VetoableChangeListenerMap map = new VetoableChangeListenerMap();

    
Constructs a VetoableChangeSupport object. 
Params:
  • sourceBean –  The bean to be given as the source for any events.
/**
     * Constructs a {@code VetoableChangeSupport} object.
     *
     * @param sourceBean  The bean to be given as the source for any events.
     */
    public VetoableChangeSupport(Object sourceBean) {
        if (sourceBean == null) {
            throw new NullPointerException();
        }
        source = sourceBean;
    }

    
Add a VetoableChangeListener to the listener list. The listener is registered for all properties. The same listener object may be added more than once, and will be called as many times as it is added. If listener is null, no exception is thrown and no action is taken. 
Params:
  • listener –  The VetoableChangeListener to be added
/**
     * Add a VetoableChangeListener to the listener list.
     * The listener is registered for all properties.
     * The same listener object may be added more than once, and will be called
     * as many times as it is added.
     * If {@code listener} is null, no exception is thrown and no action
     * is taken.
     *
     * @param listener  The VetoableChangeListener to be added
     */
    public void addVetoableChangeListener(VetoableChangeListener listener) {
        if (listener == null) {
            return;
        }
        if (listener instanceof VetoableChangeListenerProxy) {
            VetoableChangeListenerProxy proxy =
                    (VetoableChangeListenerProxy)listener;
            // Call two argument add method.
            addVetoableChangeListener(proxy.getPropertyName(),
                                      proxy.getListener());
        } else {
            this.map.add(null, listener);
        }
    }

    
Remove a VetoableChangeListener from the listener list. This removes a VetoableChangeListener that was registered for all properties. If listener was added more than once to the same event source, it will be notified one less time after being removed. If listener is null, or was never added, no exception is thrown and no action is taken. 
Params:
  • listener –  The VetoableChangeListener to be removed
/**
     * Remove a VetoableChangeListener from the listener list.
     * This removes a VetoableChangeListener that was registered
     * for all properties.
     * If {@code listener} was added more than once to the same event
     * source, it will be notified one less time after being removed.
     * If {@code listener} is null, or was never added, no exception is
     * thrown and no action is taken.
     *
     * @param listener  The VetoableChangeListener to be removed
     */
    public void removeVetoableChangeListener(VetoableChangeListener listener) {
        if (listener == null) {
            return;
        }
        if (listener instanceof VetoableChangeListenerProxy) {
            VetoableChangeListenerProxy proxy =
                    (VetoableChangeListenerProxy)listener;
            // Call two argument remove method.
            removeVetoableChangeListener(proxy.getPropertyName(),
                                         proxy.getListener());
        } else {
            this.map.remove(null, listener);
        }
    }

    
Returns an array of all the listeners that were added to the
VetoableChangeSupport object with addVetoableChangeListener().

 If some listeners have been added with a named property, then the returned array will be a mixture of VetoableChangeListeners and VetoableChangeListenerProxys. If the calling method is interested in distinguishing the listeners then it must test each element to see if it's a VetoableChangeListenerProxy, perform the cast, and examine the parameter. 

VetoableChangeListener[] listeners = bean.getVetoableChangeListeners();
for (int i = 0; i < listeners.length; i++) {
       if (listeners[i] instanceof VetoableChangeListenerProxy) {
    VetoableChangeListenerProxy proxy =
                   (VetoableChangeListenerProxy)listeners[i];
    if (proxy.getPropertyName().equals("foo")) {
      // proxy is a VetoableChangeListener which was associated
      // with the property named "foo"
    }
  }
 }



See Also:
Returns:all of the VetoableChangeListeners added or an empty array if no listeners have been added
Since:1.4
/**
     * Returns an array of all the listeners that were added to the
     * VetoableChangeSupport object with addVetoableChangeListener().
     * <p>
     * If some listeners have been added with a named property, then
     * the returned array will be a mixture of VetoableChangeListeners
     * and {@code VetoableChangeListenerProxy}s. If the calling
     * method is interested in distinguishing the listeners then it must
     * test each element to see if it's a
     * {@code VetoableChangeListenerProxy}, perform the cast, and examine
     * the parameter.
     *
     * <pre>{@code
     * VetoableChangeListener[] listeners = bean.getVetoableChangeListeners();
     * for (int i = 0; i < listeners.length; i++) {
     *        if (listeners[i] instanceof VetoableChangeListenerProxy) {
     *     VetoableChangeListenerProxy proxy =
     *                    (VetoableChangeListenerProxy)listeners[i];
     *     if (proxy.getPropertyName().equals("foo")) {
     *       // proxy is a VetoableChangeListener which was associated
     *       // with the property named "foo"
     *     }
     *   }
     * }
     * }</pre>
     *
     * @see VetoableChangeListenerProxy
     * @return all of the {@code VetoableChangeListeners} added or an
     *         empty array if no listeners have been added
     * @since 1.4
     */
    public VetoableChangeListener[] getVetoableChangeListeners(){
        return this.map.getListeners();
    }

    
Add a VetoableChangeListener for a specific property. The listener will be invoked only when a call on fireVetoableChange names that specific property. The same listener object may be added more than once. For each property, the listener will be invoked the number of times it was added for that property. If propertyName or listener is null, no exception is thrown and no action is taken. 
Params:
  • propertyName –  The name of the property to listen on.
  • listener –  The VetoableChangeListener to be added
Since:1.2
/**
     * Add a VetoableChangeListener for a specific property.  The listener
     * will be invoked only when a call on fireVetoableChange names that
     * specific property.
     * The same listener object may be added more than once.  For each
     * property,  the listener will be invoked the number of times it was added
     * for that property.
     * If {@code propertyName} or {@code listener} is null, no
     * exception is thrown and no action is taken.
     *
     * @param propertyName  The name of the property to listen on.
     * @param listener  The VetoableChangeListener to be added
     * @since 1.2
     */
    public void addVetoableChangeListener(
                                String propertyName,
                VetoableChangeListener listener) {
        if (listener == null || propertyName == null) {
            return;
        }
        listener = this.map.extract(listener);
        if (listener != null) {
            this.map.add(propertyName, listener);
        }
    }

    
Remove a VetoableChangeListener for a specific property. If listener was added more than once to the same event source for the specified property, it will be notified one less time after being removed. If propertyName is null, no exception is thrown and no action is taken. If listener is null, or was never added for the specified property, no exception is thrown and no action is taken. 
Params:
  • propertyName –  The name of the property that was listened on.
  • listener –  The VetoableChangeListener to be removed
Since:1.2
/**
     * Remove a VetoableChangeListener for a specific property.
     * If {@code listener} was added more than once to the same event
     * source for the specified property, it will be notified one less time
     * after being removed.
     * If {@code propertyName} is null, no exception is thrown and no
     * action is taken.
     * If {@code listener} is null, or was never added for the specified
     * property, no exception is thrown and no action is taken.
     *
     * @param propertyName  The name of the property that was listened on.
     * @param listener  The VetoableChangeListener to be removed
     * @since 1.2
     */
    public void removeVetoableChangeListener(
                                String propertyName,
                VetoableChangeListener listener) {
        if (listener == null || propertyName == null) {
            return;
        }
        listener = this.map.extract(listener);
        if (listener != null) {
            this.map.remove(propertyName, listener);
        }
    }

    
Returns an array of all the listeners which have been associated
with the named property.

Params:
  • propertyName –  The name of the property being listened to
Returns:all the VetoableChangeListeners associated with the named property. If no such listeners have been added, or if propertyName is null, an empty array is returned.
Since:1.4
/**
     * Returns an array of all the listeners which have been associated
     * with the named property.
     *
     * @param propertyName  The name of the property being listened to
     * @return all the {@code VetoableChangeListeners} associated with
     *         the named property.  If no such listeners have been added,
     *         or if {@code propertyName} is null, an empty array is
     *         returned.
     * @since 1.4
     */
    public VetoableChangeListener[] getVetoableChangeListeners(String propertyName) {
        return this.map.getListeners(propertyName);
    }

    
Reports a constrained property update to listeners
that have been registered to track updates of
all properties or a property with the specified name.

 Any listener can throw a PropertyVetoException to veto the update. If one of the listeners vetoes the update, this method passes a new "undo" PropertyChangeEvent that reverts to the old value to all listeners that already confirmed this update and throws the PropertyVetoException again. 

No event is fired if old and new values are equal and non-null.

 This is merely a convenience wrapper around the more general fireVetoableChange(PropertyChangeEvent) method. 
Params:
  • propertyName –  the programmatic name of the property that is about to change
  • oldValue –      the old value of the property
  • newValue –      the new value of the property
Throws:
/**
     * Reports a constrained property update to listeners
     * that have been registered to track updates of
     * all properties or a property with the specified name.
     * <p>
     * Any listener can throw a {@code PropertyVetoException} to veto the update.
     * If one of the listeners vetoes the update, this method passes
     * a new "undo" {@code PropertyChangeEvent} that reverts to the old value
     * to all listeners that already confirmed this update
     * and throws the {@code PropertyVetoException} again.
     * <p>
     * No event is fired if old and new values are equal and non-null.
     * <p>
     * This is merely a convenience wrapper around the more general
     * {@link #fireVetoableChange(PropertyChangeEvent)} method.
     *
     * @param propertyName  the programmatic name of the property that is about to change
     * @param oldValue      the old value of the property
     * @param newValue      the new value of the property
     * @throws PropertyVetoException if one of listeners vetoes the property update
     */
    public void fireVetoableChange(String propertyName, Object oldValue, Object newValue)
            throws PropertyVetoException {
        if (oldValue == null || newValue == null || !oldValue.equals(newValue)) {
            fireVetoableChange(new PropertyChangeEvent(this.source, propertyName, oldValue, newValue));
        }
    }

    
Reports an integer constrained property update to listeners
that have been registered to track updates of
all properties or a property with the specified name.

 Any listener can throw a PropertyVetoException to veto the update. If one of the listeners vetoes the update, this method passes a new "undo" PropertyChangeEvent that reverts to the old value to all listeners that already confirmed this update and throws the PropertyVetoException again. 

No event is fired if old and new values are equal.

 This is merely a convenience wrapper around the more general fireVetoableChange(String, Object, Object) method. 
Params:
  • propertyName –  the programmatic name of the property that is about to change
  • oldValue –      the old value of the property
  • newValue –      the new value of the property
Throws:
Since:1.2
/**
     * Reports an integer constrained property update to listeners
     * that have been registered to track updates of
     * all properties or a property with the specified name.
     * <p>
     * Any listener can throw a {@code PropertyVetoException} to veto the update.
     * If one of the listeners vetoes the update, this method passes
     * a new "undo" {@code PropertyChangeEvent} that reverts to the old value
     * to all listeners that already confirmed this update
     * and throws the {@code PropertyVetoException} again.
     * <p>
     * No event is fired if old and new values are equal.
     * <p>
     * This is merely a convenience wrapper around the more general
     * {@link #fireVetoableChange(String, Object, Object)} method.
     *
     * @param propertyName  the programmatic name of the property that is about to change
     * @param oldValue      the old value of the property
     * @param newValue      the new value of the property
     * @throws PropertyVetoException if one of listeners vetoes the property update
     * @since 1.2
     */
    public void fireVetoableChange(String propertyName, int oldValue, int newValue)
            throws PropertyVetoException {
        if (oldValue != newValue) {
            fireVetoableChange(propertyName, Integer.valueOf(oldValue), Integer.valueOf(newValue));
        }
    }

    
Reports a boolean constrained property update to listeners
that have been registered to track updates of
all properties or a property with the specified name.

 Any listener can throw a PropertyVetoException to veto the update. If one of the listeners vetoes the update, this method passes a new "undo" PropertyChangeEvent that reverts to the old value to all listeners that already confirmed this update and throws the PropertyVetoException again. 

No event is fired if old and new values are equal.

 This is merely a convenience wrapper around the more general fireVetoableChange(String, Object, Object) method. 
Params:
  • propertyName –  the programmatic name of the property that is about to change
  • oldValue –      the old value of the property
  • newValue –      the new value of the property
Throws:
Since:1.2
/**
     * Reports a boolean constrained property update to listeners
     * that have been registered to track updates of
     * all properties or a property with the specified name.
     * <p>
     * Any listener can throw a {@code PropertyVetoException} to veto the update.
     * If one of the listeners vetoes the update, this method passes
     * a new "undo" {@code PropertyChangeEvent} that reverts to the old value
     * to all listeners that already confirmed this update
     * and throws the {@code PropertyVetoException} again.
     * <p>
     * No event is fired if old and new values are equal.
     * <p>
     * This is merely a convenience wrapper around the more general
     * {@link #fireVetoableChange(String, Object, Object)} method.
     *
     * @param propertyName  the programmatic name of the property that is about to change
     * @param oldValue      the old value of the property
     * @param newValue      the new value of the property
     * @throws PropertyVetoException if one of listeners vetoes the property update
     * @since 1.2
     */
    public void fireVetoableChange(String propertyName, boolean oldValue, boolean newValue)
            throws PropertyVetoException {
        if (oldValue != newValue) {
            fireVetoableChange(propertyName, Boolean.valueOf(oldValue), Boolean.valueOf(newValue));
        }
    }

    
Fires a property change event to listeners
that have been registered to track updates of
all properties or a property with the specified name.

 Any listener can throw a PropertyVetoException to veto the update. If one of the listeners vetoes the update, this method passes a new "undo" PropertyChangeEvent that reverts to the old value to all listeners that already confirmed this update and throws the PropertyVetoException again. 

No event is fired if the given event's old and new values are equal and non-null.

Params:
  • event –  the PropertyChangeEvent to be fired
Throws:
Since:1.2
/**
     * Fires a property change event to listeners
     * that have been registered to track updates of
     * all properties or a property with the specified name.
     * <p>
     * Any listener can throw a {@code PropertyVetoException} to veto the update.
     * If one of the listeners vetoes the update, this method passes
     * a new "undo" {@code PropertyChangeEvent} that reverts to the old value
     * to all listeners that already confirmed this update
     * and throws the {@code PropertyVetoException} again.
     * <p>
     * No event is fired if the given event's old and new values are equal and non-null.
     *
     * @param event  the {@code PropertyChangeEvent} to be fired
     * @throws PropertyVetoException if one of listeners vetoes the property update
     * @since 1.2
     */
    public void fireVetoableChange(PropertyChangeEvent event)
            throws PropertyVetoException {
        Object oldValue = event.getOldValue();
        Object newValue = event.getNewValue();
        if (oldValue == null || newValue == null || !oldValue.equals(newValue)) {
            String name = event.getPropertyName();

            VetoableChangeListener[] common = this.map.get(null);
            VetoableChangeListener[] named = (name != null)
                        ? this.map.get(name)
                        : null;

            VetoableChangeListener[] listeners;
            if (common == null) {
                listeners = named;
            }
            else if (named == null) {
                listeners = common;
            }
            else {
                listeners = new VetoableChangeListener[common.length + named.length];
                System.arraycopy(common, 0, listeners, 0, common.length);
                System.arraycopy(named, 0, listeners, common.length, named.length);
            }
            if (listeners != null) {
                int current = 0;
                try {
                    while (current < listeners.length) {
                        listeners[current].vetoableChange(event);
                        current++;
                    }
                }
                catch (PropertyVetoException veto) {
                    event = new PropertyChangeEvent(this.source, name, newValue, oldValue);
                    for (int i = 0; i < current; i++) {
                        try {
                            listeners[i].vetoableChange(event);
                        }
                        catch (PropertyVetoException exception) {
                            // ignore exceptions that occur during rolling back
                        }
                    }
                    throw veto; // rethrow the veto exception
                }
            }
        }
    }

    
Check if there are any listeners for a specific property, including those registered on all properties. If propertyName is null, only check for listeners registered on all properties. 
Params:
  • propertyName –  the property name.
Returns:true if there are one or more listeners for the given property
Since:1.2
/**
     * Check if there are any listeners for a specific property, including
     * those registered on all properties.  If {@code propertyName}
     * is null, only check for listeners registered on all properties.
     *
     * @param propertyName  the property name.
     * @return true if there are one or more listeners for the given property
     * @since 1.2
     */
    public boolean hasListeners(String propertyName) {
        return this.map.hasListeners(propertyName);
    }

    
@serialDataNull terminated list of VetoableChangeListeners. 

At serialization time we skip non-serializable listeners and
only serialize the serializable listeners.
/**
     * @serialData Null terminated list of {@code VetoableChangeListeners}.
     * <p>
     * At serialization time we skip non-serializable listeners and
     * only serialize the serializable listeners.
     */
    private void writeObject(ObjectOutputStream s) throws IOException {
        Hashtable<String, VetoableChangeSupport> children = null;
        VetoableChangeListener[] listeners = null;
        synchronized (this.map) {
            for (Entry<String, VetoableChangeListener[]> entry : this.map.getEntries()) {
                String property = entry.getKey();
                if (property == null) {
                    listeners = entry.getValue();
                } else {
                    if (children == null) {
                        children = new Hashtable<>();
                    }
                    VetoableChangeSupport vcs = new VetoableChangeSupport(this.source);
                    vcs.map.set(null, entry.getValue());
                    children.put(property, vcs);
                }
            }
        }
        ObjectOutputStream.PutField fields = s.putFields();
        fields.put("children", children);
        fields.put("source", this.source);
        fields.put("vetoableChangeSupportSerializedDataVersion", 2);
        s.writeFields();

        if (listeners != null) {
            for (VetoableChangeListener l : listeners) {
                if (l instanceof Serializable) {
                    s.writeObject(l);
                }
            }
        }
        s.writeObject(null);
    }

    private void readObject(ObjectInputStream s) throws ClassNotFoundException, IOException {
        this.map = new VetoableChangeListenerMap();

        ObjectInputStream.GetField fields = s.readFields();

        @SuppressWarnings("unchecked")
        Hashtable<String, VetoableChangeSupport> children = (Hashtable<String, VetoableChangeSupport>)fields.get("children", null);
        this.source = fields.get("source", null);
        fields.get("vetoableChangeSupportSerializedDataVersion", 2);

        Object listenerOrNull;
        while (null != (listenerOrNull = s.readObject())) {
            this.map.add(null, (VetoableChangeListener)listenerOrNull);
        }
        if (children != null) {
            for (Entry<String, VetoableChangeSupport> entry : children.entrySet()) {
                for (VetoableChangeListener listener : entry.getValue().getVetoableChangeListeners()) {
                    this.map.add(entry.getKey(), listener);
                }
            }
        }
    }

    
The object to be provided as the "source" for any generated events.

/**
     * The object to be provided as the "source" for any generated events.
     */
    private Object source;

    
@serialFieldchildren                                   Hashtable
@serialFieldsource                                     Object
@serialFieldvetoableChangeSupportSerializedDataVersion int
/**
     * @serialField children                                   Hashtable
     * @serialField source                                     Object
     * @serialField vetoableChangeSupportSerializedDataVersion int
     */
    private static final ObjectStreamField[] serialPersistentFields = {
            new ObjectStreamField("children", Hashtable.class),
            new ObjectStreamField("source", Object.class),
            new ObjectStreamField("vetoableChangeSupportSerializedDataVersion", Integer.TYPE)
    };

    
Serialization version ID, so we're compatible with JDK 1.1

/**
     * Serialization version ID, so we're compatible with JDK 1.1
     */
    static final long serialVersionUID = -5090210921595982017L;

    
This is a ChangeListenerMap implementation that works with VetoableChangeListener objects. 
/**
     * This is a {@link ChangeListenerMap ChangeListenerMap} implementation
     * that works with {@link VetoableChangeListener VetoableChangeListener} objects.
     */
    private static final class VetoableChangeListenerMap extends ChangeListenerMap<VetoableChangeListener> {
        private static final VetoableChangeListener[] EMPTY = {};

        
Creates an array of VetoableChangeListener objects. This method uses the same instance of the empty array when length equals 0. 
Params:
  • length –  the array length
Returns:       an array with specified length
/**
         * Creates an array of {@link VetoableChangeListener VetoableChangeListener} objects.
         * This method uses the same instance of the empty array
         * when {@code length} equals {@code 0}.
         *
         * @param length  the array length
         * @return        an array with specified length
         */
        @Override
        protected VetoableChangeListener[] newArray(int length) {
            return (0 < length)
                    ? new VetoableChangeListener[length]
                    : EMPTY;
        }

        
Creates a VetoableChangeListenerProxy object for the specified property. 
Params:
  • name –      the name of the property to listen on
  • listener –  the listener to process events
Returns: a VetoableChangeListenerProxy object
/**
         * Creates a {@link VetoableChangeListenerProxy VetoableChangeListenerProxy}
         * object for the specified property.
         *
         * @param name      the name of the property to listen on
         * @param listener  the listener to process events
         * @return          a {@code VetoableChangeListenerProxy} object
         */
        @Override
        protected VetoableChangeListener newProxy(String name, VetoableChangeListener listener) {
            return new VetoableChangeListenerProxy(name, listener);
        }

        
{@inheritDoc}

/**
         * {@inheritDoc}
         */
        public VetoableChangeListener extract(VetoableChangeListener listener) {
            while (listener instanceof VetoableChangeListenerProxy) {
                listener = ((VetoableChangeListenerProxy) listener).getListener();
            }
            return listener;
        }
    }
}