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) 
class io.netty.resolver.dns.DnsResolveContext$3 implements io.netty.util.concurrent.FutureListener<io.netty.channel.AddressedEnvelope<io.netty.handler.codec.dns.DnsResponse, java.net.InetSocketAddress>>
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: io.netty.resolver.dns.DnsResolveContext$3
  super_class: java.lang.Object
{
  final io.netty.resolver.dns.DnsResolveContext this$0;
    descriptor: Lio/netty/resolver/dns/DnsResolveContext;
    flags: (0x1010) ACC_FINAL, ACC_SYNTHETIC

  private final io.netty.util.concurrent.Promise val$promise;
    descriptor: Lio/netty/util/concurrent/Promise;
    flags: (0x1012) ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC

  private final io.netty.resolver.dns.DnsQueryLifecycleObserver val$queryLifecycleObserver;
    descriptor: Lio/netty/resolver/dns/DnsQueryLifecycleObserver;
    flags: (0x1012) ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC

  private final io.netty.resolver.dns.DnsServerAddressStream val$nameServerAddrStream;
    descriptor: Lio/netty/resolver/dns/DnsServerAddressStream;
    flags: (0x1012) ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC

  private final int val$nameServerAddrStreamIndex;
    descriptor: I
    flags: (0x1012) ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC

  private final io.netty.handler.codec.dns.DnsQuestion val$question;
    descriptor: Lio/netty/handler/codec/dns/DnsQuestion;
    flags: (0x1012) ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC

  void <init>(io.netty.resolver.dns.DnsResolveContext, io.netty.util.concurrent.Promise, io.netty.resolver.dns.DnsQueryLifecycleObserver, io.netty.resolver.dns.DnsServerAddressStream, int, io.netty.handler.codec.dns.DnsQuestion);
    descriptor: (Lio/netty/resolver/dns/DnsResolveContext;Lio/netty/util/concurrent/Promise;Lio/netty/resolver/dns/DnsQueryLifecycleObserver;Lio/netty/resolver/dns/DnsServerAddressStream;ILio/netty/handler/codec/dns/DnsQuestion;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=7, args_size=7
        start local 0 // io.netty.resolver.dns.DnsResolveContext$3 this
         0: .line 350
            aload 0 /* this */
            aload 1
            putfield io.netty.resolver.dns.DnsResolveContext$3.this$0:Lio/netty/resolver/dns/DnsResolveContext;
            aload 0 /* this */
            aload 2
            putfield io.netty.resolver.dns.DnsResolveContext$3.val$promise:Lio/netty/util/concurrent/Promise;
            aload 0 /* this */
            aload 3
            putfield io.netty.resolver.dns.DnsResolveContext$3.val$queryLifecycleObserver:Lio/netty/resolver/dns/DnsQueryLifecycleObserver;
            aload 0 /* this */
            aload 4
            putfield io.netty.resolver.dns.DnsResolveContext$3.val$nameServerAddrStream:Lio/netty/resolver/dns/DnsServerAddressStream;
            aload 0 /* this */
            iload 5
            putfield io.netty.resolver.dns.DnsResolveContext$3.val$nameServerAddrStreamIndex:I
            aload 0 /* this */
            aload 6
            putfield io.netty.resolver.dns.DnsResolveContext$3.val$question:Lio/netty/handler/codec/dns/DnsQuestion;
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // io.netty.resolver.dns.DnsResolveContext$3 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lio/netty/resolver/dns/DnsResolveContext$3;
    MethodParameters:
                               Name  Flags
      this$0                         final
      val$promise                    final
      val$queryLifecycleObserver     final
      val$nameServerAddrStream       final
      val$nameServerAddrStreamIndex  final
      val$question                   final

  public void operationComplete(io.netty.util.concurrent.Future<io.netty.channel.AddressedEnvelope<io.netty.handler.codec.dns.DnsResponse, java.net.InetSocketAddress>>);
    descriptor: (Lio/netty/util/concurrent/Future;)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=7, locals=4, args_size=2
        start local 0 // io.netty.resolver.dns.DnsResolveContext$3 this
        start local 1 // io.netty.util.concurrent.Future future
         0: .line 353
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.this$0:Lio/netty/resolver/dns/DnsResolveContext;
            getfield io.netty.resolver.dns.DnsResolveContext.queriesInProgress:Ljava/util/Set;
            aload 1 /* future */
            invokeinterface java.util.Set.remove:(Ljava/lang/Object;)Z
            pop
         1: .line 355
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$promise:Lio/netty/util/concurrent/Promise;
            invokeinterface io.netty.util.concurrent.Promise.isDone:()Z
            ifne 2
            aload 1 /* future */
            invokeinterface io.netty.util.concurrent.Future.isCancelled:()Z
            ifeq 7
         2: .line 356
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$queryLifecycleObserver:Lio/netty/resolver/dns/DnsQueryLifecycleObserver;
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.this$0:Lio/netty/resolver/dns/DnsResolveContext;
            getfield io.netty.resolver.dns.DnsResolveContext.allowedQueries:I
            invokeinterface io.netty.resolver.dns.DnsQueryLifecycleObserver.queryCancelled:(I)V
         3: .line 360
            aload 1 /* future */
            invokeinterface io.netty.util.concurrent.Future.getNow:()Ljava/lang/Object;
            checkcast io.netty.channel.AddressedEnvelope
            astore 2 /* result */
        start local 2 // io.netty.channel.AddressedEnvelope result
         4: .line 361
            aload 2 /* result */
            ifnull 6
         5: .line 362
            aload 2 /* result */
            invokeinterface io.netty.channel.AddressedEnvelope.release:()Z
            pop
         6: .line 364
      StackMap locals: io.netty.channel.AddressedEnvelope
      StackMap stack:
            return
        end local 2 // io.netty.channel.AddressedEnvelope result
         7: .line 367
      StackMap locals:
      StackMap stack:
            aload 1 /* future */
            invokeinterface io.netty.util.concurrent.Future.cause:()Ljava/lang/Throwable;
            astore 2 /* queryCause */
        start local 2 // java.lang.Throwable queryCause
         8: .line 369
            aload 2 /* queryCause */
            ifnonnull 13
         9: .line 370
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.this$0:Lio/netty/resolver/dns/DnsResolveContext;
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$nameServerAddrStream:Lio/netty/resolver/dns/DnsServerAddressStream;
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$nameServerAddrStreamIndex:I
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$question:Lio/netty/handler/codec/dns/DnsQuestion;
            aload 1 /* future */
            invokeinterface io.netty.util.concurrent.Future.getNow:()Ljava/lang/Object;
            checkcast io.netty.channel.AddressedEnvelope
        10: .line 371
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$queryLifecycleObserver:Lio/netty/resolver/dns/DnsQueryLifecycleObserver;
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$promise:Lio/netty/util/concurrent/Promise;
        11: .line 370
            invokevirtual io.netty.resolver.dns.DnsResolveContext.onResponse:(Lio/netty/resolver/dns/DnsServerAddressStream;ILio/netty/handler/codec/dns/DnsQuestion;Lio/netty/channel/AddressedEnvelope;Lio/netty/resolver/dns/DnsQueryLifecycleObserver;Lio/netty/util/concurrent/Promise;)V
        12: .line 372
            goto 22
        13: .line 374
      StackMap locals: java.lang.Throwable
      StackMap stack:
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$queryLifecycleObserver:Lio/netty/resolver/dns/DnsQueryLifecycleObserver;
            aload 2 /* queryCause */
            invokeinterface io.netty.resolver.dns.DnsQueryLifecycleObserver.queryFailed:(Ljava/lang/Throwable;)V
        14: .line 375
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.this$0:Lio/netty/resolver/dns/DnsResolveContext;
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$nameServerAddrStream:Lio/netty/resolver/dns/DnsServerAddressStream;
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$nameServerAddrStreamIndex:I
            iconst_1
            iadd
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$question:Lio/netty/handler/codec/dns/DnsQuestion;
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$promise:Lio/netty/util/concurrent/Promise;
            aload 2 /* queryCause */
            invokevirtual io.netty.resolver.dns.DnsResolveContext.query:(Lio/netty/resolver/dns/DnsServerAddressStream;ILio/netty/handler/codec/dns/DnsQuestion;Lio/netty/util/concurrent/Promise;Ljava/lang/Throwable;)V
        15: .line 377
            goto 22
      StackMap locals:
      StackMap stack: java.lang.Throwable
        16: astore 3
        17: .line 378
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.this$0:Lio/netty/resolver/dns/DnsResolveContext;
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$nameServerAddrStream:Lio/netty/resolver/dns/DnsServerAddressStream;
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$nameServerAddrStreamIndex:I
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$question:Lio/netty/handler/codec/dns/DnsQuestion;
        18: .line 381
            getstatic io.netty.resolver.dns.NoopDnsQueryLifecycleObserver.INSTANCE:Lio/netty/resolver/dns/NoopDnsQueryLifecycleObserver;
        19: .line 382
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$promise:Lio/netty/util/concurrent/Promise;
            aload 2 /* queryCause */
        20: .line 378
            invokevirtual io.netty.resolver.dns.DnsResolveContext.tryToFinishResolve:(Lio/netty/resolver/dns/DnsServerAddressStream;ILio/netty/handler/codec/dns/DnsQuestion;Lio/netty/resolver/dns/DnsQueryLifecycleObserver;Lio/netty/util/concurrent/Promise;Ljava/lang/Throwable;)V
        21: .line 383
            aload 3
            athrow
        22: .line 378
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.this$0:Lio/netty/resolver/dns/DnsResolveContext;
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$nameServerAddrStream:Lio/netty/resolver/dns/DnsServerAddressStream;
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$nameServerAddrStreamIndex:I
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$question:Lio/netty/handler/codec/dns/DnsQuestion;
        23: .line 381
            getstatic io.netty.resolver.dns.NoopDnsQueryLifecycleObserver.INSTANCE:Lio/netty/resolver/dns/NoopDnsQueryLifecycleObserver;
        24: .line 382
            aload 0 /* this */
            getfield io.netty.resolver.dns.DnsResolveContext$3.val$promise:Lio/netty/util/concurrent/Promise;
            aload 2 /* queryCause */
        25: .line 378
            invokevirtual io.netty.resolver.dns.DnsResolveContext.tryToFinishResolve:(Lio/netty/resolver/dns/DnsServerAddressStream;ILio/netty/handler/codec/dns/DnsQuestion;Lio/netty/resolver/dns/DnsQueryLifecycleObserver;Lio/netty/util/concurrent/Promise;Ljava/lang/Throwable;)V
        26: .line 384
            return
        end local 2 // java.lang.Throwable queryCause
        end local 1 // io.netty.util.concurrent.Future future
        end local 0 // io.netty.resolver.dns.DnsResolveContext$3 this
      LocalVariableTable:
        Start  End  Slot        Name  Signature
            0   27     0        this  Lio/netty/resolver/dns/DnsResolveContext$3;
            0   27     1      future  Lio/netty/util/concurrent/Future<Lio/netty/channel/AddressedEnvelope<Lio/netty/handler/codec/dns/DnsResponse;Ljava/net/InetSocketAddress;>;>;
            4    7     2      result  Lio/netty/channel/AddressedEnvelope<Lio/netty/handler/codec/dns/DnsResponse;Ljava/net/InetSocketAddress;>;
            8   27     2  queryCause  Ljava/lang/Throwable;
      Exception table:
        from    to  target  type
           8    16      16  any
    Signature: (Lio/netty/util/concurrent/Future<Lio/netty/channel/AddressedEnvelope<Lio/netty/handler/codec/dns/DnsResponse;Ljava/net/InetSocketAddress;>;>;)V
    MethodParameters:
        Name  Flags
      future  
}
Signature: Ljava/lang/Object;Lio/netty/util/concurrent/FutureListener<Lio/netty/channel/AddressedEnvelope<Lio/netty/handler/codec/dns/DnsResponse;Ljava/net/InetSocketAddress;>;>;
SourceFile: "DnsResolveContext.java"
EnclosingMethod: io.netty.resolver.dns.DnsResolveContext.query:(Lio/netty/resolver/dns/DnsServerAddressStream;ILio/netty/handler/codec/dns/DnsQuestion;Lio/netty/resolver/dns/DnsQueryLifecycleObserver;Lio/netty/util/concurrent/Promise;Ljava/lang/Throwable;)V
NestHost: io.netty.resolver.dns.DnsResolveContext
InnerClasses:
  io.netty.resolver.dns.DnsResolveContext$3