https://www.graalvm.org/ 
class com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1 extends com.oracle.truffle.api.nodes.RootNode
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1
  super_class: com.oracle.truffle.api.nodes.RootNode
{
  private com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$MultiSourceBlock block;
    descriptor: Lcom/oracle/truffle/api/instrumentation/test/SourceListenerTest$MultiSourceASTLanguage$MultiSourceBlock;
    flags: (0x0002) ACC_PRIVATE
    RuntimeVisibleAnnotations: 
      com.oracle.truffle.api.nodes.Node$Child()

  final com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage this$1;
    descriptor: Lcom/oracle/truffle/api/instrumentation/test/SourceListenerTest$MultiSourceASTLanguage;
    flags: (0x1010) ACC_FINAL, ACC_SYNTHETIC

  private final com.oracle.truffle.api.source.Source val$source;
    descriptor: Lcom/oracle/truffle/api/source/Source;
    flags: (0x1012) ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC

  void <init>(com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage, com.oracle.truffle.api.TruffleLanguage, com.oracle.truffle.api.source.Source);
    descriptor: (Lcom/oracle/truffle/api/instrumentation/test/SourceListenerTest$MultiSourceASTLanguage;Lcom/oracle/truffle/api/TruffleLanguage;Lcom/oracle/truffle/api/source/Source;)V
    flags: (0x0000) 
    Code:
      stack=5, locals=4, args_size=4
        start local 0 // com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1 this
        start local 2 // com.oracle.truffle.api.TruffleLanguage $anonymous0
         0: .line 1262
            aload 0 /* this */
            aload 1
            putfield com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1.this$1:Lcom/oracle/truffle/api/instrumentation/test/SourceListenerTest$MultiSourceASTLanguage;
            aload 0 /* this */
            aload 3
            putfield com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1.val$source:Lcom/oracle/truffle/api/source/Source;
            aload 0 /* this */
            aload 2 /* $anonymous0 */
            invokespecial com.oracle.truffle.api.nodes.RootNode.<init>:(Lcom/oracle/truffle/api/TruffleLanguage;)V
         1: .line 1263
            aload 0 /* this */
            new com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$MultiSourceBlock
            dup
            aload 3
            aload 3
            invokevirtual com.oracle.truffle.api.source.Source.getCharacters:()Ljava/lang/CharSequence;
            invokeinterface java.lang.CharSequence.toString:()Ljava/lang/String;
            invokespecial com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$MultiSourceBlock.<init>:(Lcom/oracle/truffle/api/source/Source;Ljava/lang/String;)V
            putfield com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1.block:Lcom/oracle/truffle/api/instrumentation/test/SourceListenerTest$MultiSourceASTLanguage$MultiSourceBlock;
         2: .line 1262
            return
        end local 2 // com.oracle.truffle.api.TruffleLanguage $anonymous0
        end local 0 // com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1 this
      LocalVariableTable:
        Start  End  Slot         Name  Signature
            0    3     0         this  Lcom/oracle/truffle/api/instrumentation/test/SourceListenerTest$MultiSourceASTLanguage$1;
            0    3     2  $anonymous0  Lcom/oracle/truffle/api/TruffleLanguage<*>;
    MethodParameters:
             Name  Flags
      this$0       final
      $anonymous0  
      val$source   final

  public java.lang.Object execute(com.oracle.truffle.api.frame.VirtualFrame);
    descriptor: (Lcom/oracle/truffle/api/frame/VirtualFrame;)Ljava/lang/Object;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1 this
        start local 1 // com.oracle.truffle.api.frame.VirtualFrame frame
         0: .line 1267
            aload 0 /* this */
            getfield com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1.block:Lcom/oracle/truffle/api/instrumentation/test/SourceListenerTest$MultiSourceASTLanguage$MultiSourceBlock;
            aload 1 /* frame */
            invokevirtual com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$MultiSourceBlock.execute:(Lcom/oracle/truffle/api/frame/VirtualFrame;)Ljava/lang/Object;
            areturn
        end local 1 // com.oracle.truffle.api.frame.VirtualFrame frame
        end local 0 // com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1 this
      LocalVariableTable:
        Start  End  Slot   Name  Signature
            0    1     0   this  Lcom/oracle/truffle/api/instrumentation/test/SourceListenerTest$MultiSourceASTLanguage$1;
            0    1     1  frame  Lcom/oracle/truffle/api/frame/VirtualFrame;
    MethodParameters:
       Name  Flags
      frame  

  public com.oracle.truffle.api.source.SourceSection getSourceSection();
    descriptor: ()Lcom/oracle/truffle/api/source/SourceSection;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=1, args_size=1
        start local 0 // com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1 this
         0: .line 1272
            aload 0 /* this */
            getfield com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1.val$source:Lcom/oracle/truffle/api/source/Source;
            iconst_1
            invokevirtual com.oracle.truffle.api.source.Source.createSection:(I)Lcom/oracle/truffle/api/source/SourceSection;
            areturn
        end local 0 // com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/oracle/truffle/api/instrumentation/test/SourceListenerTest$MultiSourceASTLanguage$1;
}
SourceFile: "SourceListenerTest.java"
EnclosingMethod: com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage.parse:(Lcom/oracle/truffle/api/TruffleLanguage$ParsingRequest;)Lcom/oracle/truffle/api/CallTarget;
NestHost: com.oracle.truffle.api.instrumentation.test.SourceListenerTest
InnerClasses:
  public final ParsingRequest = com.oracle.truffle.api.TruffleLanguage$ParsingRequest of com.oracle.truffle.api.TruffleLanguage
  MultiSourceASTLanguage = com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage of com.oracle.truffle.api.instrumentation.test.SourceListenerTest
  com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$1
  MultiSourceBlock = com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage$MultiSourceBlock of com.oracle.truffle.api.instrumentation.test.SourceListenerTest$MultiSourceASTLanguage
  public abstract Child = com.oracle.truffle.api.nodes.Node$Child of com.oracle.truffle.api.nodes.Node