https://www.graalvm.org/ 
class com.oracle.truffle.polyglot.PolyglotImpl$2 implements java.util.function.Function<com.oracle.truffle.api.source.Source, org.graalvm.polyglot.Source>
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: com.oracle.truffle.polyglot.PolyglotImpl$2
  super_class: java.lang.Object
{
  final com.oracle.truffle.polyglot.PolyglotImpl this$0;
    descriptor: Lcom/oracle/truffle/polyglot/PolyglotImpl;
    flags: (0x1010) ACC_FINAL, ACC_SYNTHETIC

  void <init>(com.oracle.truffle.polyglot.PolyglotImpl);
    descriptor: (Lcom/oracle/truffle/polyglot/PolyglotImpl;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // com.oracle.truffle.polyglot.PolyglotImpl$2 this
         0: .line 104
            aload 0 /* this */
            aload 1
            putfield com.oracle.truffle.polyglot.PolyglotImpl$2.this$0:Lcom/oracle/truffle/polyglot/PolyglotImpl;
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // com.oracle.truffle.polyglot.PolyglotImpl$2 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/oracle/truffle/polyglot/PolyglotImpl$2;
    MethodParameters:
        Name  Flags
      this$0  final

  public org.graalvm.polyglot.Source apply(com.oracle.truffle.api.source.Source);
    descriptor: (Lcom/oracle/truffle/api/source/Source;)Lorg/graalvm/polyglot/Source;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // com.oracle.truffle.polyglot.PolyglotImpl$2 this
        start local 1 // com.oracle.truffle.api.source.Source t
         0: .line 106
            aload 0 /* this */
            getfield com.oracle.truffle.polyglot.PolyglotImpl$2.this$0:Lcom/oracle/truffle/polyglot/PolyglotImpl;
            invokevirtual com.oracle.truffle.polyglot.PolyglotImpl.getAPIAccess:()Lorg/graalvm/polyglot/impl/AbstractPolyglotImpl$APIAccess;
            aload 1 /* t */
            invokevirtual org.graalvm.polyglot.impl.AbstractPolyglotImpl$APIAccess.newSource:(Ljava/lang/Object;)Lorg/graalvm/polyglot/Source;
            areturn
        end local 1 // com.oracle.truffle.api.source.Source t
        end local 0 // com.oracle.truffle.polyglot.PolyglotImpl$2 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/oracle/truffle/polyglot/PolyglotImpl$2;
            0    1     1     t  Lcom/oracle/truffle/api/source/Source;
    MethodParameters:
      Name  Flags
      t     

  public java.lang.Object apply(java.lang.Object);
    descriptor: (Ljava/lang/Object;)Ljava/lang/Object;
    flags: (0x1041) ACC_PUBLIC, ACC_BRIDGE, ACC_SYNTHETIC
    Code:
      stack=2, locals=2, args_size=2
         0: .line 1
            aload 0
            aload 1
            checkcast com.oracle.truffle.api.source.Source
            invokevirtual com.oracle.truffle.polyglot.PolyglotImpl$2.apply:(Lcom/oracle/truffle/api/source/Source;)Lorg/graalvm/polyglot/Source;
            areturn
      LocalVariableTable:
        Start  End  Slot  Name  Signature
}
Signature: Ljava/lang/Object;Ljava/util/function/Function<Lcom/oracle/truffle/api/source/Source;Lorg/graalvm/polyglot/Source;>;
SourceFile: "PolyglotImpl.java"
EnclosingMethod: com.oracle.truffle.polyglot.PolyglotImpl
NestHost: com.oracle.truffle.polyglot.PolyglotImpl
InnerClasses:
  com.oracle.truffle.polyglot.PolyglotImpl$2
  public abstract APIAccess = org.graalvm.polyglot.impl.AbstractPolyglotImpl$APIAccess of org.graalvm.polyglot.impl.AbstractPolyglotImpl