https://www.graalvm.org/ 
public abstract class com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator<K, V>
  minor version: 0
  major version: 59
  flags: flags: (0x0421) ACC_PUBLIC, ACC_SUPER, ACC_ABSTRACT
  this_class: com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator
  super_class: java.lang.Object
{
  private final boolean forward;
    descriptor: Z
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final com.oracle.truffle.object.LinkedImmutableMap<K, V> map;
    descriptor: Lcom/oracle/truffle/object/LinkedImmutableMap;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL
    Signature: Lcom/oracle/truffle/object/LinkedImmutableMap<TK;TV;>;

  private com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry<K, V> next;
    descriptor: Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedEntry;
    flags: (0x0002) ACC_PRIVATE
    Signature: Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedEntry<TK;TV;>;

  void <init>(com.oracle.truffle.object.LinkedImmutableMap<K, V>, com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry<K, V>, );
    descriptor: (Lcom/oracle/truffle/object/LinkedImmutableMap;Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedEntry;Z)V
    flags: (0x0000) 
    Code:
      stack=2, locals=4, args_size=4
        start local 0 // com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator this
        start local 1 // com.oracle.truffle.object.LinkedImmutableMap map
        start local 2 // com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry start
        start local 3 // boolean forward
         0: .line 70
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
         1: .line 71
            aload 0 /* this */
            iload 3 /* forward */
            putfield com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator.forward:Z
         2: .line 72
            aload 0 /* this */
            aload 1 /* map */
            putfield com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator.map:Lcom/oracle/truffle/object/LinkedImmutableMap;
         3: .line 73
            aload 0 /* this */
            aload 2 /* start */
            putfield com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator.next:Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedEntry;
         4: .line 74
            return
        end local 3 // boolean forward
        end local 2 // com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry start
        end local 1 // com.oracle.truffle.object.LinkedImmutableMap map
        end local 0 // com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    5     0     this  Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedIterator<TK;TV;>;
            0    5     1      map  Lcom/oracle/truffle/object/LinkedImmutableMap<TK;TV;>;
            0    5     2    start  Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedEntry<TK;TV;>;
            0    5     3  forward  Z
    Signature: (Lcom/oracle/truffle/object/LinkedImmutableMap<TK;TV;>;Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedEntry<TK;TV;>;Z)V
    MethodParameters:
         Name  Flags
      map      
      start    
      forward  

  public final boolean hasNext();
    descriptor: ()Z
    flags: (0x0011) ACC_PUBLIC, ACC_FINAL
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator this
         0: .line 77
            aload 0 /* this */
            getfield com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator.next:Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedEntry;
            ifnull 1
            iconst_1
            ireturn
      StackMap locals:
      StackMap stack:
         1: iconst_0
            ireturn
        end local 0 // com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    2     0  this  Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedIterator<TK;TV;>;

  final com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry<K, V> nextEntry();
    descriptor: ()Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedEntry;
    flags: (0x0010) ACC_FINAL
    Code:
      stack=3, locals=3, args_size=1
        start local 0 // com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator this
         0: .line 81
            aload 0 /* this */
            getfield com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator.next:Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedEntry;
            astore 1 /* e */
        start local 1 // com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry e
         1: .line 82
            aload 1 /* e */
            ifnonnull 3
         2: .line 83
            new java.util.NoSuchElementException
            dup
            invokespecial java.util.NoSuchElementException.<init>:()V
            athrow
         3: .line 85
      StackMap locals: com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry
      StackMap stack:
            aload 0 /* this */
            getfield com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator.forward:Z
            ifeq 4
            aload 1 /* e */
            invokeinterface com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry.getNextKey:()Ljava/lang/Object;
            goto 5
      StackMap locals:
      StackMap stack:
         4: aload 1 /* e */
            invokeinterface com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry.getPrevKey:()Ljava/lang/Object;
      StackMap locals:
      StackMap stack: java.lang.Object
         5: astore 2 /* nextKey */
        start local 2 // java.lang.Object nextKey
         6: .line 86
            aload 0 /* this */
            aload 2 /* nextKey */
            ifnonnull 7
            aconst_null
            goto 8
      StackMap locals: com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry java.lang.Object
      StackMap stack: com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator
         7: aload 0 /* this */
            getfield com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator.map:Lcom/oracle/truffle/object/LinkedImmutableMap;
            aload 2 /* nextKey */
            invokeinterface com.oracle.truffle.object.LinkedImmutableMap.getEntry:(Ljava/lang/Object;)Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedEntry;
      StackMap locals: com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry java.lang.Object
      StackMap stack: com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry
         8: putfield com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator.next:Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedEntry;
         9: .line 87
            aload 1 /* e */
            areturn
        end local 2 // java.lang.Object nextKey
        end local 1 // com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry e
        end local 0 // com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0   10     0     this  Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedIterator<TK;TV;>;
            1   10     1        e  Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedEntry<TK;TV;>;
            6   10     2  nextKey  TK;
    Signature: ()Lcom/oracle/truffle/object/LinkedImmutableMap$LinkedEntry<TK;TV;>;
}
Signature: <K:Ljava/lang/Object;V:Ljava/lang/Object;>Ljava/lang/Object;
SourceFile: "LinkedImmutableMap.java"
NestHost: com.oracle.truffle.object.LinkedImmutableMap
InnerClasses:
  public abstract LinkedEntry = com.oracle.truffle.object.LinkedImmutableMap$LinkedEntry of com.oracle.truffle.object.LinkedImmutableMap
  public abstract LinkedIterator = com.oracle.truffle.object.LinkedImmutableMap$LinkedIterator of com.oracle.truffle.object.LinkedImmutableMap