https://www.graalvm.org/ 
public interface com.oracle.truffle.sl.test.SLJavaInteropTest$Pair
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: com.oracle.truffle.sl.test.SLJavaInteropTest$Pair
  super_class: java.lang.Object
{
  public abstract java.lang.String key();
    descriptor: ()Ljava/lang/String;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT

  public abstract int value();
    descriptor: ()I
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
}
SourceFile: "SLJavaInteropTest.java"
NestHost: com.oracle.truffle.sl.test.SLJavaInteropTest
InnerClasses:
  public abstract Pair = com.oracle.truffle.sl.test.SLJavaInteropTest$Pair of com.oracle.truffle.sl.test.SLJavaInteropTest