http://netty.io/netty-all/: Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers and clients. (The Netty Project) 
public abstract class io.netty.handler.codec.MessageToMessageCodec<INBOUND_IN, OUTBOUND_IN> extends io.netty.channel.ChannelDuplexHandler
  minor version: 0
  major version: 59
  flags: flags: (0x0421) ACC_PUBLIC, ACC_SUPER, ACC_ABSTRACT
  this_class: io.netty.handler.codec.MessageToMessageCodec
  super_class: io.netty.channel.ChannelDuplexHandler
{
  private final io.netty.handler.codec.MessageToMessageEncoder<java.lang.Object> encoder;
    descriptor: Lio/netty/handler/codec/MessageToMessageEncoder;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL
    Signature: Lio/netty/handler/codec/MessageToMessageEncoder<Ljava/lang/Object;>;

  private final io.netty.handler.codec.MessageToMessageDecoder<java.lang.Object> decoder;
    descriptor: Lio/netty/handler/codec/MessageToMessageDecoder;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL
    Signature: Lio/netty/handler/codec/MessageToMessageDecoder<Ljava/lang/Object;>;

  private final io.netty.util.internal.TypeParameterMatcher inboundMsgMatcher;
    descriptor: Lio/netty/util/internal/TypeParameterMatcher;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final io.netty.util.internal.TypeParameterMatcher outboundMsgMatcher;
    descriptor: Lio/netty/util/internal/TypeParameterMatcher;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  protected void <init>();
    descriptor: ()V
    flags: (0x0004) ACC_PROTECTED
    Code:
      stack=4, locals=1, args_size=1
        start local 0 // io.netty.handler.codec.MessageToMessageCodec this
         0: .line 92
            aload 0 /* this */
            invokespecial io.netty.channel.ChannelDuplexHandler.<init>:()V
         1: .line 57
            aload 0 /* this */
            new io.netty.handler.codec.MessageToMessageCodec$1
            dup
            aload 0 /* this */
            invokespecial io.netty.handler.codec.MessageToMessageCodec$1.<init>:(Lio/netty/handler/codec/MessageToMessageCodec;)V
            putfield io.netty.handler.codec.MessageToMessageCodec.encoder:Lio/netty/handler/codec/MessageToMessageEncoder;
         2: .line 71
            aload 0 /* this */
            new io.netty.handler.codec.MessageToMessageCodec$2
            dup
            aload 0 /* this */
            invokespecial io.netty.handler.codec.MessageToMessageCodec$2.<init>:(Lio/netty/handler/codec/MessageToMessageCodec;)V
            putfield io.netty.handler.codec.MessageToMessageCodec.decoder:Lio/netty/handler/codec/MessageToMessageDecoder;
         3: .line 93
            aload 0 /* this */
            aload 0 /* this */
            ldc Lio/netty/handler/codec/MessageToMessageCodec;
            ldc "INBOUND_IN"
            invokestatic io.netty.util.internal.TypeParameterMatcher.find:(Ljava/lang/Object;Ljava/lang/Class;Ljava/lang/String;)Lio/netty/util/internal/TypeParameterMatcher;
            putfield io.netty.handler.codec.MessageToMessageCodec.inboundMsgMatcher:Lio/netty/util/internal/TypeParameterMatcher;
         4: .line 94
            aload 0 /* this */
            aload 0 /* this */
            ldc Lio/netty/handler/codec/MessageToMessageCodec;
            ldc "OUTBOUND_IN"
            invokestatic io.netty.util.internal.TypeParameterMatcher.find:(Ljava/lang/Object;Ljava/lang/Class;Ljava/lang/String;)Lio/netty/util/internal/TypeParameterMatcher;
            putfield io.netty.handler.codec.MessageToMessageCodec.outboundMsgMatcher:Lio/netty/util/internal/TypeParameterMatcher;
         5: .line 95
            return
        end local 0 // io.netty.handler.codec.MessageToMessageCodec this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    6     0  this  Lio/netty/handler/codec/MessageToMessageCodec<TINBOUND_IN;TOUTBOUND_IN;>;

  protected void <init>(java.lang.Class<? extends INBOUND_IN>, java.lang.Class<? extends OUTBOUND_IN>);
    descriptor: (Ljava/lang/Class;Ljava/lang/Class;)V
    flags: (0x0004) ACC_PROTECTED
    Code:
      stack=4, locals=3, args_size=3
        start local 0 // io.netty.handler.codec.MessageToMessageCodec this
        start local 1 // java.lang.Class inboundMessageType
        start local 2 // java.lang.Class outboundMessageType
         0: .line 103
            aload 0 /* this */
            invokespecial io.netty.channel.ChannelDuplexHandler.<init>:()V
         1: .line 57
            aload 0 /* this */
            new io.netty.handler.codec.MessageToMessageCodec$1
            dup
            aload 0 /* this */
            invokespecial io.netty.handler.codec.MessageToMessageCodec$1.<init>:(Lio/netty/handler/codec/MessageToMessageCodec;)V
            putfield io.netty.handler.codec.MessageToMessageCodec.encoder:Lio/netty/handler/codec/MessageToMessageEncoder;
         2: .line 71
            aload 0 /* this */
            new io.netty.handler.codec.MessageToMessageCodec$2
            dup
            aload 0 /* this */
            invokespecial io.netty.handler.codec.MessageToMessageCodec$2.<init>:(Lio/netty/handler/codec/MessageToMessageCodec;)V
            putfield io.netty.handler.codec.MessageToMessageCodec.decoder:Lio/netty/handler/codec/MessageToMessageDecoder;
         3: .line 105
            aload 0 /* this */
            aload 1 /* inboundMessageType */
            invokestatic io.netty.util.internal.TypeParameterMatcher.get:(Ljava/lang/Class;)Lio/netty/util/internal/TypeParameterMatcher;
            putfield io.netty.handler.codec.MessageToMessageCodec.inboundMsgMatcher:Lio/netty/util/internal/TypeParameterMatcher;
         4: .line 106
            aload 0 /* this */
            aload 2 /* outboundMessageType */
            invokestatic io.netty.util.internal.TypeParameterMatcher.get:(Ljava/lang/Class;)Lio/netty/util/internal/TypeParameterMatcher;
            putfield io.netty.handler.codec.MessageToMessageCodec.outboundMsgMatcher:Lio/netty/util/internal/TypeParameterMatcher;
         5: .line 107
            return
        end local 2 // java.lang.Class outboundMessageType
        end local 1 // java.lang.Class inboundMessageType
        end local 0 // io.netty.handler.codec.MessageToMessageCodec this
      LocalVariableTable:
        Start  End  Slot                 Name  Signature
            0    6     0                 this  Lio/netty/handler/codec/MessageToMessageCodec<TINBOUND_IN;TOUTBOUND_IN;>;
            0    6     1   inboundMessageType  Ljava/lang/Class<+TINBOUND_IN;>;
            0    6     2  outboundMessageType  Ljava/lang/Class<+TOUTBOUND_IN;>;
    Signature: (Ljava/lang/Class<+TINBOUND_IN;>;Ljava/lang/Class<+TOUTBOUND_IN;>;)V
    MethodParameters:
                     Name  Flags
      inboundMessageType   
      outboundMessageType  

  public void channelRead(io.netty.channel.ChannelHandlerContext, java.lang.Object);
    descriptor: (Lio/netty/channel/ChannelHandlerContext;Ljava/lang/Object;)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=3, args_size=3
        start local 0 // io.netty.handler.codec.MessageToMessageCodec this
        start local 1 // io.netty.channel.ChannelHandlerContext ctx
        start local 2 // java.lang.Object msg
         0: .line 111
            aload 0 /* this */
            getfield io.netty.handler.codec.MessageToMessageCodec.decoder:Lio/netty/handler/codec/MessageToMessageDecoder;
            aload 1 /* ctx */
            aload 2 /* msg */
            invokevirtual io.netty.handler.codec.MessageToMessageDecoder.channelRead:(Lio/netty/channel/ChannelHandlerContext;Ljava/lang/Object;)V
         1: .line 112
            return
        end local 2 // java.lang.Object msg
        end local 1 // io.netty.channel.ChannelHandlerContext ctx
        end local 0 // io.netty.handler.codec.MessageToMessageCodec this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    2     0  this  Lio/netty/handler/codec/MessageToMessageCodec<TINBOUND_IN;TOUTBOUND_IN;>;
            0    2     1   ctx  Lio/netty/channel/ChannelHandlerContext;
            0    2     2   msg  Ljava/lang/Object;
    Exceptions:
      throws java.lang.Exception
    MethodParameters:
      Name  Flags
      ctx   
      msg   

  public void write(io.netty.channel.ChannelHandlerContext, java.lang.Object, io.netty.channel.ChannelPromise);
    descriptor: (Lio/netty/channel/ChannelHandlerContext;Ljava/lang/Object;Lio/netty/channel/ChannelPromise;)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=4, args_size=4
        start local 0 // io.netty.handler.codec.MessageToMessageCodec this
        start local 1 // io.netty.channel.ChannelHandlerContext ctx
        start local 2 // java.lang.Object msg
        start local 3 // io.netty.channel.ChannelPromise promise
         0: .line 116
            aload 0 /* this */
            getfield io.netty.handler.codec.MessageToMessageCodec.encoder:Lio/netty/handler/codec/MessageToMessageEncoder;
            aload 1 /* ctx */
            aload 2 /* msg */
            aload 3 /* promise */
            invokevirtual io.netty.handler.codec.MessageToMessageEncoder.write:(Lio/netty/channel/ChannelHandlerContext;Ljava/lang/Object;Lio/netty/channel/ChannelPromise;)V
         1: .line 117
            return
        end local 3 // io.netty.channel.ChannelPromise promise
        end local 2 // java.lang.Object msg
        end local 1 // io.netty.channel.ChannelHandlerContext ctx
        end local 0 // io.netty.handler.codec.MessageToMessageCodec this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    2     0     this  Lio/netty/handler/codec/MessageToMessageCodec<TINBOUND_IN;TOUTBOUND_IN;>;
            0    2     1      ctx  Lio/netty/channel/ChannelHandlerContext;
            0    2     2      msg  Ljava/lang/Object;
            0    2     3  promise  Lio/netty/channel/ChannelPromise;
    Exceptions:
      throws java.lang.Exception
    MethodParameters:
         Name  Flags
      ctx      
      msg      
      promise  

  public boolean acceptInboundMessage(java.lang.Object);
    descriptor: (Ljava/lang/Object;)Z
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // io.netty.handler.codec.MessageToMessageCodec this
        start local 1 // java.lang.Object msg
         0: .line 125
            aload 0 /* this */
            getfield io.netty.handler.codec.MessageToMessageCodec.inboundMsgMatcher:Lio/netty/util/internal/TypeParameterMatcher;
            aload 1 /* msg */
            invokevirtual io.netty.util.internal.TypeParameterMatcher.match:(Ljava/lang/Object;)Z
            ireturn
        end local 1 // java.lang.Object msg
        end local 0 // io.netty.handler.codec.MessageToMessageCodec this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lio/netty/handler/codec/MessageToMessageCodec<TINBOUND_IN;TOUTBOUND_IN;>;
            0    1     1   msg  Ljava/lang/Object;
    Exceptions:
      throws java.lang.Exception
    MethodParameters:
      Name  Flags
      msg   

  public boolean acceptOutboundMessage(java.lang.Object);
    descriptor: (Ljava/lang/Object;)Z
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // io.netty.handler.codec.MessageToMessageCodec this
        start local 1 // java.lang.Object msg
         0: .line 134
            aload 0 /* this */
            getfield io.netty.handler.codec.MessageToMessageCodec.outboundMsgMatcher:Lio/netty/util/internal/TypeParameterMatcher;
            aload 1 /* msg */
            invokevirtual io.netty.util.internal.TypeParameterMatcher.match:(Ljava/lang/Object;)Z
            ireturn
        end local 1 // java.lang.Object msg
        end local 0 // io.netty.handler.codec.MessageToMessageCodec this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lio/netty/handler/codec/MessageToMessageCodec<TINBOUND_IN;TOUTBOUND_IN;>;
            0    1     1   msg  Ljava/lang/Object;
    Exceptions:
      throws java.lang.Exception
    MethodParameters:
      Name  Flags
      msg   

  protected abstract void encode(io.netty.channel.ChannelHandlerContext, OUTBOUND_IN, java.util.List<java.lang.Object>);
    descriptor: (Lio/netty/channel/ChannelHandlerContext;Ljava/lang/Object;Ljava/util/List;)V
    flags: (0x0404) ACC_PROTECTED, ACC_ABSTRACT
    Exceptions:
      throws java.lang.Exception
    Signature: (Lio/netty/channel/ChannelHandlerContext;TOUTBOUND_IN;Ljava/util/List<Ljava/lang/Object;>;)V
    MethodParameters:
      Name  Flags
      ctx   
      msg   
      out   

  protected abstract void decode(io.netty.channel.ChannelHandlerContext, INBOUND_IN, java.util.List<java.lang.Object>);
    descriptor: (Lio/netty/channel/ChannelHandlerContext;Ljava/lang/Object;Ljava/util/List;)V
    flags: (0x0404) ACC_PROTECTED, ACC_ABSTRACT
    Exceptions:
      throws java.lang.Exception
    Signature: (Lio/netty/channel/ChannelHandlerContext;TINBOUND_IN;Ljava/util/List<Ljava/lang/Object;>;)V
    MethodParameters:
      Name  Flags
      ctx   
      msg   
      out   
}
Signature: <INBOUND_IN:Ljava/lang/Object;OUTBOUND_IN:Ljava/lang/Object;>Lio/netty/channel/ChannelDuplexHandler;
SourceFile: "MessageToMessageCodec.java"
NestMembers:
  io.netty.handler.codec.MessageToMessageCodec$1  io.netty.handler.codec.MessageToMessageCodec$2
InnerClasses:
  io.netty.handler.codec.MessageToMessageCodec$1
  io.netty.handler.codec.MessageToMessageCodec$2