https://www.graalvm.org/ 
public interface com.oracle.truffle.js.runtime.objects.JSCopyableObject
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: com.oracle.truffle.js.runtime.objects.JSCopyableObject
  super_class: java.lang.Object
{
  public com.oracle.truffle.js.runtime.objects.JSObject copy();
    descriptor: ()Lcom/oracle/truffle/js/runtime/objects/JSObject;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=1
        start local 0 // com.oracle.truffle.js.runtime.objects.JSCopyableObject this
         0: .line 46
            aload 0 /* this */
            checkcast com.oracle.truffle.js.runtime.objects.JSObject
            astore 1 /* thisObj */
        start local 1 // com.oracle.truffle.js.runtime.objects.JSObject thisObj
         1: .line 47
            aload 1 /* thisObj */
            aload 1 /* thisObj */
            invokevirtual com.oracle.truffle.js.runtime.objects.JSObject.getShape:()Lcom/oracle/truffle/api/object/Shape;
            invokevirtual com.oracle.truffle.api.object.Shape.getRoot:()Lcom/oracle/truffle/api/object/Shape;
            invokevirtual com.oracle.truffle.js.runtime.objects.JSObject.copyWithoutProperties:(Lcom/oracle/truffle/api/object/Shape;)Lcom/oracle/truffle/js/runtime/objects/JSObject;
            aload 1 /* thisObj */
            invokestatic com.oracle.truffle.js.runtime.objects.JSObjectUtil.copyProperties:(Lcom/oracle/truffle/api/object/DynamicObject;Lcom/oracle/truffle/api/object/DynamicObject;)Lcom/oracle/truffle/api/object/DynamicObject;
            checkcast com.oracle.truffle.js.runtime.objects.JSObject
            areturn
        end local 1 // com.oracle.truffle.js.runtime.objects.JSObject thisObj
        end local 0 // com.oracle.truffle.js.runtime.objects.JSCopyableObject this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    2     0     this  Lcom/oracle/truffle/js/runtime/objects/JSCopyableObject;
            1    2     1  thisObj  Lcom/oracle/truffle/js/runtime/objects/JSObject;
}
SourceFile: "JSCopyableObject.java"