https://www.graalvm.org/ 
final class com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage extends com.oracle.truffle.api.TruffleLanguage$LanguageReference<com.oracle.truffle.api.TruffleLanguage<java.lang.Object>>
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage
  super_class: com.oracle.truffle.api.TruffleLanguage$LanguageReference
{
  private final com.oracle.truffle.polyglot.PolyglotLanguage language;
    descriptor: Lcom/oracle/truffle/polyglot/PolyglotLanguage;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private com.oracle.truffle.api.TruffleLanguage<java.lang.Object> spi;
    descriptor: Lcom/oracle/truffle/api/TruffleLanguage;
    flags: (0x0002) ACC_PRIVATE
    Signature: Lcom/oracle/truffle/api/TruffleLanguage<Ljava/lang/Object;>;
    RuntimeVisibleAnnotations: 
      com.oracle.truffle.api.CompilerDirectives$CompilationFinal()

  static final boolean $assertionsDisabled;
    descriptor: Z
    flags: (0x1018) ACC_STATIC, ACC_FINAL, ACC_SYNTHETIC

  static void <clinit>();
    descriptor: ()V
    flags: (0x0008) ACC_STATIC
    Code:
      stack=1, locals=0, args_size=0
         0: .line 181
            ldc Lcom/oracle/truffle/polyglot/PolyglotReferences;
            invokevirtual java.lang.Class.desiredAssertionStatus:()Z
            ifne 1
            iconst_1
            goto 2
      StackMap locals:
      StackMap stack:
         1: iconst_0
      StackMap locals:
      StackMap stack: int
         2: putstatic com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage.$assertionsDisabled:Z
            return
      LocalVariableTable:
        Start  End  Slot  Name  Signature

  void <init>(com.oracle.truffle.polyglot.PolyglotLanguage, com.oracle.truffle.polyglot.PolyglotLanguageInstance);
    descriptor: (Lcom/oracle/truffle/polyglot/PolyglotLanguage;Lcom/oracle/truffle/polyglot/PolyglotLanguageInstance;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=3, args_size=3
        start local 0 // com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage this
        start local 1 // com.oracle.truffle.polyglot.PolyglotLanguage language
        start local 2 // com.oracle.truffle.polyglot.PolyglotLanguageInstance initValue
         0: .line 187
            aload 0 /* this */
            invokespecial com.oracle.truffle.api.TruffleLanguage$LanguageReference.<init>:()V
         1: .line 188
            aload 0 /* this */
            aload 1 /* language */
            putfield com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage.language:Lcom/oracle/truffle/polyglot/PolyglotLanguage;
         2: .line 189
            aload 0 /* this */
            aload 2 /* initValue */
            ifnull 3
            aload 2 /* initValue */
            getfield com.oracle.truffle.polyglot.PolyglotLanguageInstance.spi:Lcom/oracle/truffle/api/TruffleLanguage;
            goto 4
      StackMap locals: com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage com.oracle.truffle.polyglot.PolyglotLanguage com.oracle.truffle.polyglot.PolyglotLanguageInstance
      StackMap stack: com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage
         3: aconst_null
      StackMap locals: com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage com.oracle.truffle.polyglot.PolyglotLanguage com.oracle.truffle.polyglot.PolyglotLanguageInstance
      StackMap stack: com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage com.oracle.truffle.api.TruffleLanguage
         4: putfield com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage.spi:Lcom/oracle/truffle/api/TruffleLanguage;
         5: .line 190
            return
        end local 2 // com.oracle.truffle.polyglot.PolyglotLanguageInstance initValue
        end local 1 // com.oracle.truffle.polyglot.PolyglotLanguage language
        end local 0 // com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage this
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0    6     0       this  Lcom/oracle/truffle/polyglot/PolyglotReferences$SingleLanguage;
            0    6     1   language  Lcom/oracle/truffle/polyglot/PolyglotLanguage;
            0    6     2  initValue  Lcom/oracle/truffle/polyglot/PolyglotLanguageInstance;
    MethodParameters:
           Name  Flags
      language   
      initValue  

  public com.oracle.truffle.api.TruffleLanguage<java.lang.Object> get();
    descriptor: ()Lcom/oracle/truffle/api/TruffleLanguage;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=2, args_size=1
        start local 0 // com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage this
         0: .line 195
            getstatic com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage.$assertionsDisabled:Z
            ifne 1
            aload 0 /* this */
            getfield com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage.language:Lcom/oracle/truffle/polyglot/PolyglotLanguage;
            invokevirtual com.oracle.truffle.polyglot.PolyglotLanguage.assertCorrectEngine:()Z
            ifne 1
            new java.lang.AssertionError
            dup
            invokespecial java.lang.AssertionError.<init>:()V
            athrow
         1: .line 196
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            getfield com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage.spi:Lcom/oracle/truffle/api/TruffleLanguage;
            astore 1 /* languageSpi */
        start local 1 // com.oracle.truffle.api.TruffleLanguage languageSpi
         2: .line 197
            aload 1 /* languageSpi */
            ifnonnull 5
         3: .line 198
            invokestatic com.oracle.truffle.api.CompilerDirectives.transferToInterpreterAndInvalidate:()V
         4: .line 199
            aload 0 /* this */
            aload 0 /* this */
            getfield com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage.language:Lcom/oracle/truffle/polyglot/PolyglotLanguage;
            invokevirtual com.oracle.truffle.polyglot.PolyglotLanguage.getCurrentLanguageContext:()Lcom/oracle/truffle/polyglot/PolyglotLanguageContext;
            invokevirtual com.oracle.truffle.polyglot.PolyglotLanguageContext.getLanguageInstance:()Lcom/oracle/truffle/polyglot/PolyglotLanguageInstance;
            getfield com.oracle.truffle.polyglot.PolyglotLanguageInstance.spi:Lcom/oracle/truffle/api/TruffleLanguage;
            dup
            astore 1 /* languageSpi */
            putfield com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage.spi:Lcom/oracle/truffle/api/TruffleLanguage;
         5: .line 201
      StackMap locals: com.oracle.truffle.api.TruffleLanguage
      StackMap stack:
            getstatic com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage.$assertionsDisabled:Z
            ifne 6
            aload 0 /* this */
            getfield com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage.language:Lcom/oracle/truffle/polyglot/PolyglotLanguage;
            aload 1 /* languageSpi */
            invokestatic com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage.assertDirectLanguageAccess:(Lcom/oracle/truffle/polyglot/PolyglotLanguage;Lcom/oracle/truffle/api/TruffleLanguage;)Z
            ifne 6
            new java.lang.AssertionError
            dup
            invokespecial java.lang.AssertionError.<init>:()V
            athrow
         6: .line 202
      StackMap locals:
      StackMap stack:
            aload 1 /* languageSpi */
            areturn
        end local 1 // com.oracle.truffle.api.TruffleLanguage languageSpi
        end local 0 // com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage this
      LocalVariableTable:
        Start  End  Slot         Name  Signature
            0    7     0         this  Lcom/oracle/truffle/polyglot/PolyglotReferences$SingleLanguage;
            2    7     1  languageSpi  Lcom/oracle/truffle/api/TruffleLanguage<Ljava/lang/Object;>;
    Signature: ()Lcom/oracle/truffle/api/TruffleLanguage<Ljava/lang/Object;>;

  private static boolean assertDirectLanguageAccess(com.oracle.truffle.polyglot.PolyglotLanguage, com.oracle.truffle.api.TruffleLanguage<java.lang.Object>);
    descriptor: (Lcom/oracle/truffle/polyglot/PolyglotLanguage;Lcom/oracle/truffle/api/TruffleLanguage;)Z
    flags: (0x000a) ACC_PRIVATE, ACC_STATIC
    Code:
      stack=2, locals=3, args_size=2
        start local 0 // com.oracle.truffle.polyglot.PolyglotLanguage language
        start local 1 // com.oracle.truffle.api.TruffleLanguage seenLanguage
         0: .line 206
            aload 0 /* language */
            invokevirtual com.oracle.truffle.polyglot.PolyglotLanguage.getConservativeLanguageReference:()Lcom/oracle/truffle/api/TruffleLanguage$LanguageReference;
            invokevirtual com.oracle.truffle.api.TruffleLanguage$LanguageReference.get:()Lcom/oracle/truffle/api/TruffleLanguage;
            astore 2 /* conservativeLanguage */
        start local 2 // com.oracle.truffle.api.TruffleLanguage conservativeLanguage
         1: .line 207
            aload 2 /* conservativeLanguage */
            aload 1 /* seenLanguage */
            if_acmpeq 3
         2: .line 208
            aload 0 /* language */
            invokevirtual com.oracle.truffle.polyglot.PolyglotLanguage.getEngine:()Lcom/oracle/truffle/polyglot/PolyglotEngineImpl;
            invokestatic com.oracle.truffle.polyglot.PolyglotReferences.invalidSharingError:(Lcom/oracle/truffle/polyglot/PolyglotEngineImpl;)Ljava/lang/AssertionError;
            athrow
         3: .line 210
      StackMap locals: com.oracle.truffle.api.TruffleLanguage
      StackMap stack:
            iconst_1
            ireturn
        end local 2 // com.oracle.truffle.api.TruffleLanguage conservativeLanguage
        end local 1 // com.oracle.truffle.api.TruffleLanguage seenLanguage
        end local 0 // com.oracle.truffle.polyglot.PolyglotLanguage language
      LocalVariableTable:
        Start  End  Slot                  Name  Signature
            0    4     0              language  Lcom/oracle/truffle/polyglot/PolyglotLanguage;
            0    4     1          seenLanguage  Lcom/oracle/truffle/api/TruffleLanguage<Ljava/lang/Object;>;
            1    4     2  conservativeLanguage  Lcom/oracle/truffle/api/TruffleLanguage<*>;
    Signature: (Lcom/oracle/truffle/polyglot/PolyglotLanguage;Lcom/oracle/truffle/api/TruffleLanguage<Ljava/lang/Object;>;)Z
    MethodParameters:
              Name  Flags
      language      
      seenLanguage  
}
Signature: Lcom/oracle/truffle/api/TruffleLanguage$LanguageReference<Lcom/oracle/truffle/api/TruffleLanguage<Ljava/lang/Object;>;>;
SourceFile: "PolyglotReferences.java"
NestHost: com.oracle.truffle.polyglot.PolyglotReferences
InnerClasses:
  public abstract CompilationFinal = com.oracle.truffle.api.CompilerDirectives$CompilationFinal of com.oracle.truffle.api.CompilerDirectives
  public abstract LanguageReference = com.oracle.truffle.api.TruffleLanguage$LanguageReference of com.oracle.truffle.api.TruffleLanguage
  private final SingleLanguage = com.oracle.truffle.polyglot.PolyglotReferences$SingleLanguage of com.oracle.truffle.polyglot.PolyglotReferences