https://www.graalvm.org/ 
class com.oracle.truffle.tck.tests.TestRun$1 implements java.util.function.Function<java.util.Map$Entry<java.lang.String, ? extends org.graalvm.polyglot.tck.Snippet>, java.lang.String>
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: com.oracle.truffle.tck.tests.TestRun$1
  super_class: java.lang.Object
{
  final com.oracle.truffle.tck.tests.TestRun this$0;
    descriptor: Lcom/oracle/truffle/tck/tests/TestRun;
    flags: (0x1010) ACC_FINAL, ACC_SYNTHETIC

  void <init>(com.oracle.truffle.tck.tests.TestRun);
    descriptor: (Lcom/oracle/truffle/tck/tests/TestRun;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // com.oracle.truffle.tck.tests.TestRun$1 this
         0: .line 143
            aload 0 /* this */
            aload 1
            putfield com.oracle.truffle.tck.tests.TestRun$1.this$0:Lcom/oracle/truffle/tck/tests/TestRun;
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // com.oracle.truffle.tck.tests.TestRun$1 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/oracle/truffle/tck/tests/TestRun$1;
    MethodParameters:
        Name  Flags
      this$0  final

  public java.lang.String apply(java.util.Map$Entry<java.lang.String, ? extends org.graalvm.polyglot.tck.Snippet>);
    descriptor: (Ljava/util/Map$Entry;)Ljava/lang/String;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=2, args_size=2
        start local 0 // com.oracle.truffle.tck.tests.TestRun$1 this
        start local 1 // java.util.Map$Entry e
         0: .line 146
            new java.lang.StringBuilder
            dup
            aload 1 /* e */
            invokeinterface java.util.Map$Entry.getKey:()Ljava/lang/Object;
            checkcast java.lang.String
            invokestatic java.lang.String.valueOf:(Ljava/lang/Object;)Ljava/lang/String;
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            ldc "::"
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            aload 1 /* e */
            invokeinterface java.util.Map$Entry.getValue:()Ljava/lang/Object;
            checkcast org.graalvm.polyglot.tck.Snippet
            invokevirtual org.graalvm.polyglot.tck.Snippet.getId:()Ljava/lang/String;
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
            areturn
        end local 1 // java.util.Map$Entry e
        end local 0 // com.oracle.truffle.tck.tests.TestRun$1 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/oracle/truffle/tck/tests/TestRun$1;
            0    1     1     e  Ljava/util/Map$Entry<Ljava/lang/String;+Lorg/graalvm/polyglot/tck/Snippet;>;
    Signature: (Ljava/util/Map$Entry<Ljava/lang/String;+Lorg/graalvm/polyglot/tck/Snippet;>;)Ljava/lang/String;
    MethodParameters:
      Name  Flags
      e     

  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 java.util.Map$Entry
            invokevirtual com.oracle.truffle.tck.tests.TestRun$1.apply:(Ljava/util/Map$Entry;)Ljava/lang/String;
            areturn
      LocalVariableTable:
        Start  End  Slot  Name  Signature
}
Signature: Ljava/lang/Object;Ljava/util/function/Function<Ljava/util/Map$Entry<Ljava/lang/String;+Lorg/graalvm/polyglot/tck/Snippet;>;Ljava/lang/String;>;
SourceFile: "TestRun.java"
EnclosingMethod: com.oracle.truffle.tck.tests.TestRun.toString:()Ljava/lang/String;
NestHost: com.oracle.truffle.tck.tests.TestRun
InnerClasses:
  com.oracle.truffle.tck.tests.TestRun$1
  public abstract Entry = java.util.Map$Entry of java.util.Map