https://www.graalvm.org/ 
public interface com.oracle.truffle.js.test.threading.AsyncTaskTests$ThenableInt
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: com.oracle.truffle.js.test.threading.AsyncTaskTests$ThenableInt
  super_class: java.lang.Object
{
  public abstract void then(org.graalvm.polyglot.Value, org.graalvm.polyglot.Value);
    descriptor: (Lorg/graalvm/polyglot/Value;Lorg/graalvm/polyglot/Value;)V
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    MethodParameters:
           Name  Flags
      onResolve  
      onReject   
}
SourceFile: "AsyncTaskTests.java"
NestHost: com.oracle.truffle.js.test.threading.AsyncTaskTests
InnerClasses:
  public abstract ThenableInt = com.oracle.truffle.js.test.threading.AsyncTaskTests$ThenableInt of com.oracle.truffle.js.test.threading.AsyncTaskTests
    RuntimeVisibleAnnotations: 
      java.lang.FunctionalInterface()