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) 
final class io.netty.util.concurrent.DefaultPromise$CauseHolder
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: io.netty.util.concurrent.DefaultPromise$CauseHolder
  super_class: java.lang.Object
{
  final java.lang.Throwable cause;
    descriptor: Ljava/lang/Throwable;
    flags: (0x0010) ACC_FINAL

  void <init>(java.lang.Throwable);
    descriptor: (Ljava/lang/Throwable;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // io.netty.util.concurrent.DefaultPromise$CauseHolder this
        start local 1 // java.lang.Throwable cause
         0: .line 757
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
         1: .line 758
            aload 0 /* this */
            aload 1 /* cause */
            putfield io.netty.util.concurrent.DefaultPromise$CauseHolder.cause:Ljava/lang/Throwable;
         2: .line 759
            return
        end local 1 // java.lang.Throwable cause
        end local 0 // io.netty.util.concurrent.DefaultPromise$CauseHolder this
      LocalVariableTable:
        Start  End  Slot   Name  Signature
            0    3     0   this  Lio/netty/util/concurrent/DefaultPromise$CauseHolder;
            0    3     1  cause  Ljava/lang/Throwable;
    MethodParameters:
       Name  Flags
      cause  
}
SourceFile: "DefaultPromise.java"
NestHost: io.netty.util.concurrent.DefaultPromise
InnerClasses:
  private final CauseHolder = io.netty.util.concurrent.DefaultPromise$CauseHolder of io.netty.util.concurrent.DefaultPromise