https://www.graalvm.org/ 
final class com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey<C extends com.oracle.truffle.llvm.runtime.ContextExtension> extends com.oracle.truffle.llvm.runtime.ContextExtension$Key<C>
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey
  super_class: com.oracle.truffle.llvm.runtime.ContextExtension$Key
{
  private static final com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey<?>[] EMPTY;
    descriptor: [Lcom/oracle/truffle/llvm/runtime/LLVMLanguage$ContextExtensionKey;
    flags: (0x001a) ACC_PRIVATE, ACC_STATIC, ACC_FINAL
    Signature: [Lcom/oracle/truffle/llvm/runtime/LLVMLanguage$ContextExtensionKey<*>;

  private final java.lang.Class<? extends C> clazz;
    descriptor: Ljava/lang/Class;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL
    Signature: Ljava/lang/Class<+TC;>;

  private final int index;
    descriptor: I
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final com.oracle.truffle.llvm.runtime.ContextExtension$Factory<C> factory;
    descriptor: Lcom/oracle/truffle/llvm/runtime/ContextExtension$Factory;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL
    Signature: Lcom/oracle/truffle/llvm/runtime/ContextExtension$Factory<TC;>;

  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 103
            ldc Lcom/oracle/truffle/llvm/runtime/LLVMLanguage;
            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.llvm.runtime.LLVMLanguage$ContextExtensionKey.$assertionsDisabled:Z
         3: .line 105
            iconst_0
            anewarray com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey
            putstatic com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey.EMPTY:[Lcom/oracle/truffle/llvm/runtime/LLVMLanguage$ContextExtensionKey;
            return
      LocalVariableTable:
        Start  End  Slot  Name  Signature

  void <init>(java.lang.Class<C>, int, com.oracle.truffle.llvm.runtime.ContextExtension$Factory<C>);
    descriptor: (Ljava/lang/Class;ILcom/oracle/truffle/llvm/runtime/ContextExtension$Factory;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=4, args_size=4
        start local 0 // com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey this
        start local 1 // java.lang.Class clazz
        start local 2 // int index
        start local 3 // com.oracle.truffle.llvm.runtime.ContextExtension$Factory factory
         0: .line 112
            aload 0 /* this */
            invokespecial com.oracle.truffle.llvm.runtime.ContextExtension$Key.<init>:()V
         1: .line 113
            aload 0 /* this */
            aload 1 /* clazz */
            putfield com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey.clazz:Ljava/lang/Class;
         2: .line 114
            aload 0 /* this */
            iload 2 /* index */
            putfield com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey.index:I
         3: .line 115
            aload 0 /* this */
            aload 3 /* factory */
            putfield com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey.factory:Lcom/oracle/truffle/llvm/runtime/ContextExtension$Factory;
         4: .line 116
            return
        end local 3 // com.oracle.truffle.llvm.runtime.ContextExtension$Factory factory
        end local 2 // int index
        end local 1 // java.lang.Class clazz
        end local 0 // com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    5     0     this  Lcom/oracle/truffle/llvm/runtime/LLVMLanguage$ContextExtensionKey<TC;>;
            0    5     1    clazz  Ljava/lang/Class<TC;>;
            0    5     2    index  I
            0    5     3  factory  Lcom/oracle/truffle/llvm/runtime/ContextExtension$Factory<TC;>;
    Signature: (Ljava/lang/Class<TC;>;ILcom/oracle/truffle/llvm/runtime/ContextExtension$Factory<TC;>;)V
    MethodParameters:
         Name  Flags
      clazz    
      index    
      factory  

  public C get(com.oracle.truffle.llvm.runtime.LLVMContext);
    descriptor: (Lcom/oracle/truffle/llvm/runtime/LLVMContext;)Lcom/oracle/truffle/llvm/runtime/ContextExtension;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=2, args_size=2
        start local 0 // com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey this
        start local 1 // com.oracle.truffle.llvm.runtime.LLVMContext ctx
         0: .line 120
            aload 0 /* this */
            getfield com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey.clazz:Ljava/lang/Class;
            invokestatic com.oracle.truffle.api.CompilerAsserts.compilationConstant:(Ljava/lang/Object;)V
         1: .line 121
            aload 0 /* this */
            getfield com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey.clazz:Ljava/lang/Class;
            aload 1 /* ctx */
            aload 0 /* this */
            getfield com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey.index:I
            invokevirtual com.oracle.truffle.llvm.runtime.LLVMContext.getContextExtension:(I)Lcom/oracle/truffle/llvm/runtime/ContextExtension;
            invokevirtual java.lang.Class.cast:(Ljava/lang/Object;)Ljava/lang/Object;
            checkcast com.oracle.truffle.llvm.runtime.ContextExtension
            areturn
        end local 1 // com.oracle.truffle.llvm.runtime.LLVMContext ctx
        end local 0 // com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    2     0  this  Lcom/oracle/truffle/llvm/runtime/LLVMLanguage$ContextExtensionKey<TC;>;
            0    2     1   ctx  Lcom/oracle/truffle/llvm/runtime/LLVMContext;
    Signature: (Lcom/oracle/truffle/llvm/runtime/LLVMContext;)TC;
    MethodParameters:
      Name  Flags
      ctx   

  private <U extends com.oracle.truffle.llvm.runtime.ContextExtension> com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey<U> cast(java.lang.Class<U>);
    descriptor: (Ljava/lang/Class;)Lcom/oracle/truffle/llvm/runtime/LLVMLanguage$ContextExtensionKey;
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=2, locals=3, args_size=2
        start local 0 // com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey this
        start local 1 // java.lang.Class target
         0: .line 126
            aload 0 /* this */
            getfield com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey.clazz:Ljava/lang/Class;
            aload 1 /* target */
            invokevirtual java.lang.Class.asSubclass:(Ljava/lang/Class;)Ljava/lang/Class;
            astore 2 /* c */
        start local 2 // java.lang.Class c
         1: .line 127
            getstatic com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey.$assertionsDisabled:Z
            ifne 2
            aload 2 /* c */
            aload 0 /* this */
            getfield com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey.clazz:Ljava/lang/Class;
            if_acmpeq 2
            new java.lang.AssertionError
            dup
            invokespecial java.lang.AssertionError.<init>:()V
            athrow
         2: .line 128
      StackMap locals: java.lang.Class
      StackMap stack:
            aload 0 /* this */
            areturn
        end local 2 // java.lang.Class c
        end local 1 // java.lang.Class target
        end local 0 // com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey this
      LocalVariableTable:
        Start  End  Slot    Name  Signature
            0    3     0    this  Lcom/oracle/truffle/llvm/runtime/LLVMLanguage$ContextExtensionKey<TC;>;
            0    3     1  target  Ljava/lang/Class<TU;>;
            1    3     2       c  Ljava/lang/Class<+TU;>;
    Signature: <U::Lcom/oracle/truffle/llvm/runtime/ContextExtension;>(Ljava/lang/Class<TU;>;)Lcom/oracle/truffle/llvm/runtime/LLVMLanguage$ContextExtensionKey<TU;>;
    MethodParameters:
        Name  Flags
      target  
}
Signature: <C::Lcom/oracle/truffle/llvm/runtime/ContextExtension;>Lcom/oracle/truffle/llvm/runtime/ContextExtension$Key<TC;>;
SourceFile: "LLVMLanguage.java"
NestHost: com.oracle.truffle.llvm.runtime.LLVMLanguage
InnerClasses:
  public abstract Factory = com.oracle.truffle.llvm.runtime.ContextExtension$Factory of com.oracle.truffle.llvm.runtime.ContextExtension
  public abstract Key = com.oracle.truffle.llvm.runtime.ContextExtension$Key of com.oracle.truffle.llvm.runtime.ContextExtension
  private final ContextExtensionKey = com.oracle.truffle.llvm.runtime.LLVMLanguage$ContextExtensionKey of com.oracle.truffle.llvm.runtime.LLVMLanguage