https://www.graalvm.org/ 
final class com.oracle.truffle.api.test.parser.OptionalElement<T, R> extends com.oracle.truffle.api.test.parser.Element<R>
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: com.oracle.truffle.api.test.parser.OptionalElement
  super_class: com.oracle.truffle.api.test.parser.Element
{
  com.oracle.truffle.api.test.parser.Element<T> element;
    descriptor: Lcom/oracle/truffle/api/test/parser/Element;
    flags: (0x0000) 
    Signature: Lcom/oracle/truffle/api/test/parser/Element<TT;>;
    RuntimeVisibleAnnotations: 
      com.oracle.truffle.api.nodes.Node$Child()

  private final java.util.function.Function<T, R> hasValueAction;
    descriptor: Ljava/util/function/Function;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL
    Signature: Ljava/util/function/Function<TT;TR;>;

  private final java.util.function.Supplier<R> hasNoValueAction;
    descriptor: Ljava/util/function/Supplier;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL
    Signature: Ljava/util/function/Supplier<TR;>;

  private final com.oracle.truffle.api.profiles.ConditionProfile seenEof;
    descriptor: Lcom/oracle/truffle/api/profiles/ConditionProfile;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  void <init>(com.oracle.truffle.api.test.parser.Element<T>, java.util.function.Function<T, R>, java.util.function.Supplier<R>);
    descriptor: (Lcom/oracle/truffle/api/test/parser/Element;Ljava/util/function/Function;Ljava/util/function/Supplier;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=4, args_size=4
        start local 0 // com.oracle.truffle.api.test.parser.OptionalElement this
        start local 1 // com.oracle.truffle.api.test.parser.Element element
        start local 2 // java.util.function.Function hasValueAction
        start local 3 // java.util.function.Supplier hasNoValueAction
         0: .line 474
            aload 0 /* this */
            invokespecial com.oracle.truffle.api.test.parser.Element.<init>:()V
         1: .line 472
            aload 0 /* this */
            invokestatic com.oracle.truffle.api.profiles.ConditionProfile.create:()Lcom/oracle/truffle/api/profiles/ConditionProfile;
            putfield com.oracle.truffle.api.test.parser.OptionalElement.seenEof:Lcom/oracle/truffle/api/profiles/ConditionProfile;
         2: .line 475
            aload 0 /* this */
            aload 1 /* element */
            putfield com.oracle.truffle.api.test.parser.OptionalElement.element:Lcom/oracle/truffle/api/test/parser/Element;
         3: .line 476
            aload 0 /* this */
            aload 2 /* hasValueAction */
            putfield com.oracle.truffle.api.test.parser.OptionalElement.hasValueAction:Ljava/util/function/Function;
         4: .line 477
            aload 0 /* this */
            aload 3 /* hasNoValueAction */
            putfield com.oracle.truffle.api.test.parser.OptionalElement.hasNoValueAction:Ljava/util/function/Supplier;
         5: .line 478
            return
        end local 3 // java.util.function.Supplier hasNoValueAction
        end local 2 // java.util.function.Function hasValueAction
        end local 1 // com.oracle.truffle.api.test.parser.Element element
        end local 0 // com.oracle.truffle.api.test.parser.OptionalElement this
      LocalVariableTable:
        Start  End  Slot              Name  Signature
            0    6     0              this  Lcom/oracle/truffle/api/test/parser/OptionalElement<TT;TR;>;
            0    6     1           element  Lcom/oracle/truffle/api/test/parser/Element<TT;>;
            0    6     2    hasValueAction  Ljava/util/function/Function<TT;TR;>;
            0    6     3  hasNoValueAction  Ljava/util/function/Supplier<TR;>;
    Signature: (Lcom/oracle/truffle/api/test/parser/Element<TT;>;Ljava/util/function/Function<TT;TR;>;Ljava/util/function/Supplier<TR;>;)V
    MethodParameters:
                  Name  Flags
      element           
      hasValueAction    
      hasNoValueAction  

  protected void createFirstSet(com.oracle.truffle.api.test.parser.Element<?>, java.util.HashSet<com.oracle.truffle.api.test.parser.Rule<?>>);
    descriptor: (Lcom/oracle/truffle/api/test/parser/Element;Ljava/util/HashSet;)V
    flags: (0x0004) ACC_PROTECTED
    Code:
      stack=3, locals=3, args_size=3
        start local 0 // com.oracle.truffle.api.test.parser.OptionalElement this
        start local 1 // com.oracle.truffle.api.test.parser.Element setHolder
        start local 2 // java.util.HashSet rulesAdded
         0: .line 482
            new java.lang.IllegalStateException
            dup
            ldc "should not reach here"
            invokespecial java.lang.IllegalStateException.<init>:(Ljava/lang/String;)V
            athrow
        end local 2 // java.util.HashSet rulesAdded
        end local 1 // com.oracle.truffle.api.test.parser.Element setHolder
        end local 0 // com.oracle.truffle.api.test.parser.OptionalElement this
      LocalVariableTable:
        Start  End  Slot        Name  Signature
            0    1     0        this  Lcom/oracle/truffle/api/test/parser/OptionalElement<TT;TR;>;
            0    1     1   setHolder  Lcom/oracle/truffle/api/test/parser/Element<*>;
            0    1     2  rulesAdded  Ljava/util/HashSet<Lcom/oracle/truffle/api/test/parser/Rule<*>;>;
    Signature: (Lcom/oracle/truffle/api/test/parser/Element<*>;Ljava/util/HashSet<Lcom/oracle/truffle/api/test/parser/Rule<*>;>;)V
    MethodParameters:
            Name  Flags
      setHolder   
      rulesAdded  

  public void initialize();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=1, args_size=1
        start local 0 // com.oracle.truffle.api.test.parser.OptionalElement this
         0: .line 487
            aload 0 /* this */
            getfield com.oracle.truffle.api.test.parser.OptionalElement.element:Lcom/oracle/truffle/api/test/parser/Element;
            aload 0 /* this */
            getfield com.oracle.truffle.api.test.parser.OptionalElement.element:Lcom/oracle/truffle/api/test/parser/Element;
            new java.util.HashSet
            dup
            invokespecial java.util.HashSet.<init>:()V
            invokevirtual com.oracle.truffle.api.test.parser.Element.createFirstSet:(Lcom/oracle/truffle/api/test/parser/Element;Ljava/util/HashSet;)V
         1: .line 488
            aload 0 /* this */
            getfield com.oracle.truffle.api.test.parser.OptionalElement.element:Lcom/oracle/truffle/api/test/parser/Element;
            invokevirtual com.oracle.truffle.api.test.parser.Element.initialize:()V
         2: .line 489
            return
        end local 0 // com.oracle.truffle.api.test.parser.OptionalElement this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    3     0  this  Lcom/oracle/truffle/api/test/parser/OptionalElement<TT;TR;>;

  public R consume(com.oracle.truffle.api.test.parser.PELexer);
    descriptor: (Lcom/oracle/truffle/api/test/parser/PELexer;)Ljava/lang/Object;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=3, args_size=2
        start local 0 // com.oracle.truffle.api.test.parser.OptionalElement this
        start local 1 // com.oracle.truffle.api.test.parser.PELexer lexer
         0: .line 493
            aload 1 /* lexer */
            aload 0 /* this */
            getfield com.oracle.truffle.api.test.parser.OptionalElement.seenEof:Lcom/oracle/truffle/api/profiles/ConditionProfile;
            invokevirtual com.oracle.truffle.api.test.parser.PELexer.peek:(Lcom/oracle/truffle/api/profiles/ConditionProfile;)B
            istore 2 /* lookahead */
        start local 2 // byte lookahead
         1: .line 494
            aload 0 /* this */
            getfield com.oracle.truffle.api.test.parser.OptionalElement.element:Lcom/oracle/truffle/api/test/parser/Element;
            iload 2 /* lookahead */
            invokevirtual com.oracle.truffle.api.test.parser.Element.canStartWith:(B)Z
            ifeq 3
         2: .line 495
            aload 0 /* this */
            getfield com.oracle.truffle.api.test.parser.OptionalElement.hasValueAction:Ljava/util/function/Function;
            aload 0 /* this */
            getfield com.oracle.truffle.api.test.parser.OptionalElement.element:Lcom/oracle/truffle/api/test/parser/Element;
            aload 1 /* lexer */
            invokevirtual com.oracle.truffle.api.test.parser.Element.consume:(Lcom/oracle/truffle/api/test/parser/PELexer;)Ljava/lang/Object;
            invokeinterface java.util.function.Function.apply:(Ljava/lang/Object;)Ljava/lang/Object;
            areturn
         3: .line 497
      StackMap locals: int
      StackMap stack:
            aload 0 /* this */
            getfield com.oracle.truffle.api.test.parser.OptionalElement.hasNoValueAction:Ljava/util/function/Supplier;
            invokeinterface java.util.function.Supplier.get:()Ljava/lang/Object;
            areturn
        end local 2 // byte lookahead
        end local 1 // com.oracle.truffle.api.test.parser.PELexer lexer
        end local 0 // com.oracle.truffle.api.test.parser.OptionalElement this
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0    4     0       this  Lcom/oracle/truffle/api/test/parser/OptionalElement<TT;TR;>;
            0    4     1      lexer  Lcom/oracle/truffle/api/test/parser/PELexer;
            1    4     2  lookahead  B
    Signature: (Lcom/oracle/truffle/api/test/parser/PELexer;)TR;
    MethodParameters:
       Name  Flags
      lexer  
}
Signature: <T:Ljava/lang/Object;R:Ljava/lang/Object;>Lcom/oracle/truffle/api/test/parser/Element<TR;>;
SourceFile: "PEParser.java"
InnerClasses:
  public abstract Child = com.oracle.truffle.api.nodes.Node$Child of com.oracle.truffle.api.nodes.Node