https://www.graalvm.org/ 
final class com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet extends java.util.AbstractSet<java.lang.String>
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet
  super_class: java.util.AbstractSet
{
  private final java.lang.Object receiver;
    descriptor: Ljava/lang/Object;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final org.graalvm.polyglot.Value keys;
    descriptor: Lorg/graalvm/polyglot/Value;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private int cachedSize;
    descriptor: I
    flags: (0x0002) ACC_PRIVATE

  final com.oracle.truffle.polyglot.PolyglotValue$InteropValue this$1;
    descriptor: Lcom/oracle/truffle/polyglot/PolyglotValue$InteropValue;
    flags: (0x1010) ACC_FINAL, ACC_SYNTHETIC

  void <init>(com.oracle.truffle.polyglot.PolyglotValue$InteropValue, java.lang.Object, org.graalvm.polyglot.Value);
    descriptor: (Lcom/oracle/truffle/polyglot/PolyglotValue$InteropValue;Ljava/lang/Object;Lorg/graalvm/polyglot/Value;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=4, args_size=4
        start local 0 // com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet this
        start local 2 // java.lang.Object receiver
        start local 3 // org.graalvm.polyglot.Value keys
         0: .line 3182
            aload 0 /* this */
            aload 1
            putfield com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet.this$1:Lcom/oracle/truffle/polyglot/PolyglotValue$InteropValue;
            aload 0 /* this */
            invokespecial java.util.AbstractSet.<init>:()V
         1: .line 3180
            aload 0 /* this */
            iconst_m1
            putfield com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet.cachedSize:I
         2: .line 3183
            aload 0 /* this */
            aload 2 /* receiver */
            putfield com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet.receiver:Ljava/lang/Object;
         3: .line 3184
            aload 0 /* this */
            aload 3 /* keys */
            putfield com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet.keys:Lorg/graalvm/polyglot/Value;
         4: .line 3185
            return
        end local 3 // org.graalvm.polyglot.Value keys
        end local 2 // java.lang.Object receiver
        end local 0 // com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet this
      LocalVariableTable:
        Start  End  Slot      Name  Signature
            0    5     0      this  Lcom/oracle/truffle/polyglot/PolyglotValue$InteropValue$MemberSet;
            0    5     2  receiver  Ljava/lang/Object;
            0    5     3      keys  Lorg/graalvm/polyglot/Value;
    MethodParameters:
          Name  Flags
      this$0    final
      receiver  
      keys      

  public boolean contains(java.lang.Object);
    descriptor: (Ljava/lang/Object;)Z
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=2, args_size=2
        start local 0 // com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet this
        start local 1 // java.lang.Object o
         0: .line 3189
            aload 1 /* o */
            instanceof java.lang.String
            ifne 2
         1: .line 3190
            iconst_0
            ireturn
         2: .line 3192
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            getfield com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet.this$1:Lcom/oracle/truffle/polyglot/PolyglotValue$InteropValue;
            aload 0 /* this */
            getfield com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet.receiver:Ljava/lang/Object;
            aload 1 /* o */
            checkcast java.lang.String
            invokevirtual com.oracle.truffle.polyglot.PolyglotValue$InteropValue.hasMember:(Ljava/lang/Object;Ljava/lang/String;)Z
            ireturn
        end local 1 // java.lang.Object o
        end local 0 // com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    3     0  this  Lcom/oracle/truffle/polyglot/PolyglotValue$InteropValue$MemberSet;
            0    3     1     o  Ljava/lang/Object;
    MethodParameters:
      Name  Flags
      o     

  public java.util.Iterator<java.lang.String> iterator();
    descriptor: ()Ljava/util/Iterator;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=1, args_size=1
        start local 0 // com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet this
         0: .line 3197
            new com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet$1
            dup
            aload 0 /* this */
            invokespecial com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet$1.<init>:(Lcom/oracle/truffle/polyglot/PolyglotValue$InteropValue$MemberSet;)V
            areturn
        end local 0 // com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/oracle/truffle/polyglot/PolyglotValue$InteropValue$MemberSet;
    Signature: ()Ljava/util/Iterator<Ljava/lang/String;>;

  public int size();
    descriptor: ()I
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=2, args_size=1
        start local 0 // com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet this
         0: .line 3221
            aload 0 /* this */
            getfield com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet.cachedSize:I
            istore 1 /* size */
        start local 1 // int size
         1: .line 3222
            iload 1 /* size */
            iconst_m1
            if_icmpeq 3
         2: .line 3223
            iload 1 /* size */
            ireturn
         3: .line 3225
      StackMap locals: int
      StackMap stack:
            aload 0 /* this */
            aload 0 /* this */
            getfield com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet.keys:Lorg/graalvm/polyglot/Value;
            invokevirtual org.graalvm.polyglot.Value.getArraySize:()J
            l2i
            dup
            istore 1 /* size */
            putfield com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet.cachedSize:I
         4: .line 3226
            iload 1 /* size */
            ireturn
        end local 1 // int size
        end local 0 // com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    5     0  this  Lcom/oracle/truffle/polyglot/PolyglotValue$InteropValue$MemberSet;
            1    5     1  size  I
}
Signature: Ljava/util/AbstractSet<Ljava/lang/String;>;
SourceFile: "PolyglotValue.java"
NestHost: com.oracle.truffle.polyglot.PolyglotValue
InnerClasses:
  private final InteropValue = com.oracle.truffle.polyglot.PolyglotValue$InteropValue of com.oracle.truffle.polyglot.PolyglotValue
  private final MemberSet = com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet of com.oracle.truffle.polyglot.PolyglotValue$InteropValue
  com.oracle.truffle.polyglot.PolyglotValue$InteropValue$MemberSet$1