https://github.com/google/guava/guava: Guava is a suite of core and expanded libraries that include utility classes, google's collections, io classes, and much much more. 
class com.google.common.util.concurrent.ServiceManager$1 implements com.google.common.util.concurrent.ListenerCallQueue$Event<com.google.common.util.concurrent.ServiceManager$Listener>
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: com.google.common.util.concurrent.ServiceManager$1
  super_class: java.lang.Object
{
  void <init>();
    descriptor: ()V
    flags: (0x0000) 
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // com.google.common.util.concurrent.ServiceManager$1 this
         0: .line 127
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // com.google.common.util.concurrent.ServiceManager$1 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/util/concurrent/ServiceManager$1;

  public void call(com.google.common.util.concurrent.ServiceManager$Listener);
    descriptor: (Lcom/google/common/util/concurrent/ServiceManager$Listener;)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=2, args_size=2
        start local 0 // com.google.common.util.concurrent.ServiceManager$1 this
        start local 1 // com.google.common.util.concurrent.ServiceManager$Listener listener
         0: .line 130
            aload 1 /* listener */
            invokevirtual com.google.common.util.concurrent.ServiceManager$Listener.healthy:()V
         1: .line 131
            return
        end local 1 // com.google.common.util.concurrent.ServiceManager$Listener listener
        end local 0 // com.google.common.util.concurrent.ServiceManager$1 this
      LocalVariableTable:
        Start  End  Slot      Name  Signature
            0    2     0      this  Lcom/google/common/util/concurrent/ServiceManager$1;
            0    2     1  listener  Lcom/google/common/util/concurrent/ServiceManager$Listener;
    MethodParameters:
          Name  Flags
      listener  

  public java.lang.String toString();
    descriptor: ()Ljava/lang/String;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // com.google.common.util.concurrent.ServiceManager$1 this
         0: .line 135
            ldc "healthy()"
            areturn
        end local 0 // com.google.common.util.concurrent.ServiceManager$1 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/util/concurrent/ServiceManager$1;

  public void call(java.lang.Object);
    descriptor: (Ljava/lang/Object;)V
    flags: (0x1041) ACC_PUBLIC, ACC_BRIDGE, ACC_SYNTHETIC
    Code:
      stack=2, locals=2, args_size=2
         0: .line 1
            aload 0
            aload 1
            checkcast com.google.common.util.concurrent.ServiceManager$Listener
            invokevirtual com.google.common.util.concurrent.ServiceManager$1.call:(Lcom/google/common/util/concurrent/ServiceManager$Listener;)V
            return
      LocalVariableTable:
        Start  End  Slot  Name  Signature
}
Signature: Ljava/lang/Object;Lcom/google/common/util/concurrent/ListenerCallQueue$Event<Lcom/google/common/util/concurrent/ServiceManager$Listener;>;
SourceFile: "ServiceManager.java"
EnclosingMethod: com.google.common.util.concurrent.ServiceManager
NestHost: com.google.common.util.concurrent.ServiceManager
InnerClasses:
  abstract Event = com.google.common.util.concurrent.ListenerCallQueue$Event of com.google.common.util.concurrent.ListenerCallQueue
  com.google.common.util.concurrent.ServiceManager$1
  public abstract Listener = com.google.common.util.concurrent.ServiceManager$Listener of com.google.common.util.concurrent.ServiceManager