https://www.graalvm.org/ 
public class com.oracle.truffle.js.test.instrumentation.GR21608
  minor version: 0
  major version: 59
  flags: flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: com.oracle.truffle.js.test.instrumentation.GR21608
  super_class: java.lang.Object
{
  public void <init>();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // com.oracle.truffle.js.test.instrumentation.GR21608 this
         0: .line 51
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // com.oracle.truffle.js.test.instrumentation.GR21608 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/oracle/truffle/js/test/instrumentation/GR21608;

  public void testIt();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=2, args_size=1
        start local 0 // com.oracle.truffle.js.test.instrumentation.GR21608 this
         0: .line 55
            iconst_0
            anewarray java.lang.String
            invokestatic com.oracle.truffle.js.test.instrumentation.TestUtil.newContextBuilder:([Ljava/lang/String;)Lorg/graalvm/polyglot/Context$Builder;
            invokevirtual org.graalvm.polyglot.Context$Builder.build:()Lorg/graalvm/polyglot/Context;
            astore 1 /* context */
        start local 1 // org.graalvm.polyglot.Context context
         1: .line 57
            aload 1 /* context */
            invokevirtual org.graalvm.polyglot.Context.getEngine:()Lorg/graalvm/polyglot/Engine;
            invokevirtual org.graalvm.polyglot.Engine.getInstruments:()Ljava/util/Map;
            ldc "DummyInstrument1"
            invokeinterface java.util.Map.get:(Ljava/lang/Object;)Ljava/lang/Object;
            checkcast org.graalvm.polyglot.Instrument
            ldc Lcom/oracle/truffle/js/test/instrumentation/GR21608$DummyInstrument1;
            invokevirtual org.graalvm.polyglot.Instrument.lookup:(Ljava/lang/Class;)Ljava/lang/Object;
            pop
         2: .line 58
            aload 1 /* context */
            ldc "js"
            ldc "(function() {})();"
            invokevirtual org.graalvm.polyglot.Context.eval:(Ljava/lang/String;Ljava/lang/CharSequence;)Lorg/graalvm/polyglot/Value;
            pop
         3: .line 60
            aload 1 /* context */
            invokevirtual org.graalvm.polyglot.Context.getEngine:()Lorg/graalvm/polyglot/Engine;
            invokevirtual org.graalvm.polyglot.Engine.getInstruments:()Ljava/util/Map;
            ldc "DummyInstrument2"
            invokeinterface java.util.Map.get:(Ljava/lang/Object;)Ljava/lang/Object;
            checkcast org.graalvm.polyglot.Instrument
            ldc Lcom/oracle/truffle/js/test/instrumentation/GR21608$DummyInstrument2;
            invokevirtual org.graalvm.polyglot.Instrument.lookup:(Ljava/lang/Class;)Ljava/lang/Object;
            pop
         4: .line 61
            aload 1 /* context */
            ldc "js"
            ldc "(function() {})();"
            invokevirtual org.graalvm.polyglot.Context.eval:(Ljava/lang/String;Ljava/lang/CharSequence;)Lorg/graalvm/polyglot/Value;
            pop
         5: .line 62
            return
        end local 1 // org.graalvm.polyglot.Context context
        end local 0 // com.oracle.truffle.js.test.instrumentation.GR21608 this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    6     0     this  Lcom/oracle/truffle/js/test/instrumentation/GR21608;
            1    6     1  context  Lorg/graalvm/polyglot/Context;
    RuntimeVisibleAnnotations: 
      org.junit.Test()
}
SourceFile: "GR21608.java"
NestMembers:
  com.oracle.truffle.js.test.instrumentation.GR21608$DummyInstrument1  com.oracle.truffle.js.test.instrumentation.GR21608$DummyInstrument2
InnerClasses:
  public DummyInstrument1 = com.oracle.truffle.js.test.instrumentation.GR21608$DummyInstrument1 of com.oracle.truffle.js.test.instrumentation.GR21608
  public DummyInstrument2 = com.oracle.truffle.js.test.instrumentation.GR21608$DummyInstrument2 of com.oracle.truffle.js.test.instrumentation.GR21608
  public final Builder = org.graalvm.polyglot.Context$Builder of org.graalvm.polyglot.Context