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.MessageToMessageDecoder<I> extends io.netty.channel.ChannelInboundHandlerAdapter
  minor version: 0
  major version: 59
  flags: flags: (0x0421) ACC_PUBLIC, ACC_SUPER, ACC_ABSTRACT
  this_class: io.netty.handler.codec.MessageToMessageDecoder
  super_class: io.netty.channel.ChannelInboundHandlerAdapter
{
  private final io.netty.util.internal.TypeParameterMatcher matcher;
    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.MessageToMessageDecoder this
         0: .line 59
            aload 0 /* this */
            invokespecial io.netty.channel.ChannelInboundHandlerAdapter.<init>:()V
         1: .line 60
            aload 0 /* this */
            aload 0 /* this */
            ldc Lio/netty/handler/codec/MessageToMessageDecoder;
            ldc "I"
            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.MessageToMessageDecoder.matcher:Lio/netty/util/internal/TypeParameterMatcher;
         2: .line 61
            return
        end local 0 // io.netty.handler.codec.MessageToMessageDecoder this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    3     0  this  Lio/netty/handler/codec/MessageToMessageDecoder<TI;>;

  protected void <init>(java.lang.Class<? extends I>);
    descriptor: (Ljava/lang/Class;)V
    flags: (0x0004) ACC_PROTECTED
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // io.netty.handler.codec.MessageToMessageDecoder this
        start local 1 // java.lang.Class inboundMessageType
         0: .line 68
            aload 0 /* this */
            invokespecial io.netty.channel.ChannelInboundHandlerAdapter.<init>:()V
         1: .line 69
            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.MessageToMessageDecoder.matcher:Lio/netty/util/internal/TypeParameterMatcher;
         2: .line 70
            return
        end local 1 // java.lang.Class inboundMessageType
        end local 0 // io.netty.handler.codec.MessageToMessageDecoder this
      LocalVariableTable:
        Start  End  Slot                Name  Signature
            0    3     0                this  Lio/netty/handler/codec/MessageToMessageDecoder<TI;>;
            0    3     1  inboundMessageType  Ljava/lang/Class<+TI;>;
    Signature: (Ljava/lang/Class<+TI;>;)V
    MethodParameters:
                    Name  Flags
      inboundMessageType  

  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.MessageToMessageDecoder this
        start local 1 // java.lang.Object msg
         0: .line 77
            aload 0 /* this */
            getfield io.netty.handler.codec.MessageToMessageDecoder.matcher: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.MessageToMessageDecoder this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lio/netty/handler/codec/MessageToMessageDecoder<TI;>;
            0    1     1   msg  Ljava/lang/Object;
    Exceptions:
      throws java.lang.Exception
    MethodParameters:
      Name  Flags
      msg   

  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=4, locals=9, args_size=3
        start local 0 // io.netty.handler.codec.MessageToMessageDecoder this
        start local 1 // io.netty.channel.ChannelHandlerContext ctx
        start local 2 // java.lang.Object msg
         0: .line 82
            invokestatic io.netty.handler.codec.CodecOutputList.newInstance:()Lio/netty/handler/codec/CodecOutputList;
            astore 3 /* out */
        start local 3 // io.netty.handler.codec.CodecOutputList out
         1: .line 84
            aload 0 /* this */
            aload 2 /* msg */
            invokevirtual io.netty.handler.codec.MessageToMessageDecoder.acceptInboundMessage:(Ljava/lang/Object;)Z
            ifeq 10
         2: .line 86
            aload 2 /* msg */
            astore 4 /* cast */
        start local 4 // java.lang.Object cast
         3: .line 88
            aload 0 /* this */
            aload 1 /* ctx */
            aload 4 /* cast */
            aload 3 /* out */
            invokevirtual io.netty.handler.codec.MessageToMessageDecoder.decode:(Lio/netty/channel/ChannelHandlerContext;Ljava/lang/Object;Ljava/util/List;)V
         4: .line 89
            goto 8
      StackMap locals: io.netty.handler.codec.MessageToMessageDecoder io.netty.channel.ChannelHandlerContext java.lang.Object io.netty.handler.codec.CodecOutputList java.lang.Object
      StackMap stack: java.lang.Throwable
         5: astore 5
         6: .line 90
            aload 4 /* cast */
            invokestatic io.netty.util.ReferenceCountUtil.release:(Ljava/lang/Object;)Z
            pop
         7: .line 91
            aload 5
            athrow
         8: .line 90
      StackMap locals:
      StackMap stack:
            aload 4 /* cast */
            invokestatic io.netty.util.ReferenceCountUtil.release:(Ljava/lang/Object;)Z
            pop
        end local 4 // java.lang.Object cast
         9: .line 92
            goto 25
        10: .line 93
      StackMap locals:
      StackMap stack:
            aload 3 /* out */
            aload 2 /* msg */
            invokevirtual io.netty.handler.codec.CodecOutputList.add:(Ljava/lang/Object;)Z
            pop
        11: .line 95
            goto 25
      StackMap locals:
      StackMap stack: io.netty.handler.codec.DecoderException
        12: astore 4 /* e */
        start local 4 // io.netty.handler.codec.DecoderException e
        13: .line 96
            aload 4 /* e */
            athrow
        end local 4 // io.netty.handler.codec.DecoderException e
        14: .line 97
      StackMap locals:
      StackMap stack: java.lang.Exception
            astore 4 /* e */
        start local 4 // java.lang.Exception e
        15: .line 98
            new io.netty.handler.codec.DecoderException
            dup
            aload 4 /* e */
            invokespecial io.netty.handler.codec.DecoderException.<init>:(Ljava/lang/Throwable;)V
            athrow
        end local 4 // java.lang.Exception e
        16: .line 99
      StackMap locals:
      StackMap stack: java.lang.Throwable
            astore 6
        17: .line 100
            aload 3 /* out */
            invokevirtual io.netty.handler.codec.CodecOutputList.size:()I
            istore 7 /* size */
        start local 7 // int size
        18: .line 101
            iconst_0
            istore 8 /* i */
        start local 8 // int i
        19: goto 22
        20: .line 102
      StackMap locals: io.netty.handler.codec.MessageToMessageDecoder io.netty.channel.ChannelHandlerContext java.lang.Object io.netty.handler.codec.CodecOutputList top top java.lang.Throwable int int
      StackMap stack:
            aload 1 /* ctx */
            aload 3 /* out */
            iload 8 /* i */
            invokevirtual io.netty.handler.codec.CodecOutputList.getUnsafe:(I)Ljava/lang/Object;
            invokeinterface io.netty.channel.ChannelHandlerContext.fireChannelRead:(Ljava/lang/Object;)Lio/netty/channel/ChannelHandlerContext;
            pop
        21: .line 101
            iinc 8 /* i */ 1
      StackMap locals:
      StackMap stack:
        22: iload 8 /* i */
            iload 7 /* size */
            if_icmplt 20
        end local 8 // int i
        23: .line 104
            aload 3 /* out */
            invokevirtual io.netty.handler.codec.CodecOutputList.recycle:()V
        end local 7 // int size
        24: .line 105
            aload 6
            athrow
        25: .line 100
      StackMap locals: io.netty.handler.codec.MessageToMessageDecoder io.netty.channel.ChannelHandlerContext java.lang.Object io.netty.handler.codec.CodecOutputList
      StackMap stack:
            aload 3 /* out */
            invokevirtual io.netty.handler.codec.CodecOutputList.size:()I
            istore 7 /* size */
        start local 7 // int size
        26: .line 101
            iconst_0
            istore 8 /* i */
        start local 8 // int i
        27: goto 30
        28: .line 102
      StackMap locals: io.netty.handler.codec.MessageToMessageDecoder io.netty.channel.ChannelHandlerContext java.lang.Object io.netty.handler.codec.CodecOutputList top top top int int
      StackMap stack:
            aload 1 /* ctx */
            aload 3 /* out */
            iload 8 /* i */
            invokevirtual io.netty.handler.codec.CodecOutputList.getUnsafe:(I)Ljava/lang/Object;
            invokeinterface io.netty.channel.ChannelHandlerContext.fireChannelRead:(Ljava/lang/Object;)Lio/netty/channel/ChannelHandlerContext;
            pop
        29: .line 101
            iinc 8 /* i */ 1
      StackMap locals:
      StackMap stack:
        30: iload 8 /* i */
            iload 7 /* size */
            if_icmplt 28
        end local 8 // int i
        31: .line 104
            aload 3 /* out */
            invokevirtual io.netty.handler.codec.CodecOutputList.recycle:()V
        end local 7 // int size
        32: .line 106
            return
        end local 3 // io.netty.handler.codec.CodecOutputList out
        end local 2 // java.lang.Object msg
        end local 1 // io.netty.channel.ChannelHandlerContext ctx
        end local 0 // io.netty.handler.codec.MessageToMessageDecoder this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0   33     0  this  Lio/netty/handler/codec/MessageToMessageDecoder<TI;>;
            0   33     1   ctx  Lio/netty/channel/ChannelHandlerContext;
            0   33     2   msg  Ljava/lang/Object;
            1   33     3   out  Lio/netty/handler/codec/CodecOutputList;
            3    9     4  cast  TI;
           13   14     4     e  Lio/netty/handler/codec/DecoderException;
           15   16     4     e  Ljava/lang/Exception;
           18   24     7  size  I
           26   32     7  size  I
           19   23     8     i  I
           27   31     8     i  I
      Exception table:
        from    to  target  type
           3     5       5  any
           1    11      12  Class io.netty.handler.codec.DecoderException
           1    11      14  Class java.lang.Exception
           1    16      16  any
    Exceptions:
      throws java.lang.Exception
    MethodParameters:
      Name  Flags
      ctx   
      msg   

  protected abstract void decode(io.netty.channel.ChannelHandlerContext, I, 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;TI;Ljava/util/List<Ljava/lang/Object;>;)V
    MethodParameters:
      Name  Flags
      ctx   
      msg   
      out   
}
Signature: <I:Ljava/lang/Object;>Lio/netty/channel/ChannelInboundHandlerAdapter;
SourceFile: "MessageToMessageDecoder.java"