https://www.graalvm.org/ 
final class com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck
  super_class: java.lang.Object
{
  private final java.util.Set<java.lang.ref.WeakReference<java.lang.Object>> collectibleRefs;
    descriptor: Ljava/util/Set;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL
    Signature: Ljava/util/Set<Ljava/lang/ref/WeakReference<Ljava/lang/Object;>;>;

  private final java.util.Set<java.lang.Long> threadIDs;
    descriptor: Ljava/util/Set;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL
    Signature: Ljava/util/Set<Ljava/lang/Long;>;

  void <init>();
    descriptor: ()V
    flags: (0x0000) 
    Code:
      stack=3, locals=6, args_size=1
        start local 0 // com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck this
         0: .line 67
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
         1: .line 64
            aload 0 /* this */
            new java.util.HashSet
            dup
            invokespecial java.util.HashSet.<init>:()V
            putfield com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck.collectibleRefs:Ljava/util/Set;
         2: .line 65
            aload 0 /* this */
            new java.util.HashSet
            dup
            invokespecial java.util.HashSet.<init>:()V
            putfield com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck.threadIDs:Ljava/util/Set;
         3: .line 68
            invokestatic com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck.findAllThreads:()[Ljava/lang/Thread;
            astore 1 /* threads */
        start local 1 // java.lang.Thread[] threads
         4: .line 69
            aload 1 /* threads */
            dup
            astore 5
            arraylength
            istore 4
            iconst_0
            istore 3
            goto 9
      StackMap locals: com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck java.lang.Thread[] top int int java.lang.Thread[]
      StackMap stack:
         5: aload 5
            iload 3
            aaload
            astore 2 /* t */
        start local 2 // java.lang.Thread t
         6: .line 70
            aload 2 /* t */
            ifnull 8
         7: .line 71
            aload 0 /* this */
            getfield com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck.threadIDs:Ljava/util/Set;
            aload 2 /* t */
            invokevirtual java.lang.Thread.getId:()J
            invokestatic java.lang.Long.valueOf:(J)Ljava/lang/Long;
            invokeinterface java.util.Set.add:(Ljava/lang/Object;)Z
            pop
        end local 2 // java.lang.Thread t
         8: .line 69
      StackMap locals:
      StackMap stack:
            iinc 3 1
      StackMap locals:
      StackMap stack:
         9: iload 3
            iload 4
            if_icmplt 5
        10: .line 74
            return
        end local 1 // java.lang.Thread[] threads
        end local 0 // com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0   11     0     this  Lcom/oracle/truffle/tools/chromeinspector/test/EnginesGCedTest$GCCheck;
            4   11     1  threads  [Ljava/lang/Thread;
            6    8     2        t  Ljava/lang/Thread;

  void checkCollected();
    descriptor: ()V
    flags: (0x0000) 
    Code:
      stack=3, locals=6, args_size=1
        start local 0 // com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck this
         0: .line 77
            aload 0 /* this */
            getfield com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck.collectibleRefs:Ljava/util/Set;
            invokeinterface java.util.Set.iterator:()Ljava/util/Iterator;
            astore 2
            goto 3
      StackMap locals: com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck top java.util.Iterator
      StackMap stack:
         1: aload 2
            invokeinterface java.util.Iterator.next:()Ljava/lang/Object;
            checkcast java.lang.ref.WeakReference
            astore 1 /* ref */
        start local 1 // java.lang.ref.WeakReference ref
         2: .line 78
            ldc "Not collected"
            aload 1 /* ref */
            invokestatic com.oracle.truffle.api.test.GCUtils.assertGc:(Ljava/lang/String;Ljava/lang/ref/Reference;)V
        end local 1 // java.lang.ref.WeakReference ref
         3: .line 77
      StackMap locals:
      StackMap stack:
            aload 2
            invokeinterface java.util.Iterator.hasNext:()Z
            ifne 1
         4: .line 80
            invokestatic com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck.findAllThreads:()[Ljava/lang/Thread;
            astore 1 /* threads */
        start local 1 // java.lang.Thread[] threads
         5: .line 81
            aload 1 /* threads */
            dup
            astore 5
            arraylength
            istore 4
            iconst_0
            istore 3
            goto 15
      StackMap locals: com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck java.lang.Thread[] top int int java.lang.Thread[]
      StackMap stack:
         6: aload 5
            iload 3
            aaload
            astore 2 /* t */
        start local 2 // java.lang.Thread t
         7: .line 82
            aload 2 /* t */
            ifnull 14
         8: .line 83
            aload 0 /* this */
            getfield com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck.threadIDs:Ljava/util/Set;
            aload 2 /* t */
            invokevirtual java.lang.Thread.getId:()J
            invokestatic java.lang.Long.valueOf:(J)Ljava/lang/Long;
            invokeinterface java.util.Set.contains:(Ljava/lang/Object;)Z
            ifne 14
         9: .line 84
            aload 2 /* t */
            invokevirtual java.lang.Object.getClass:()Ljava/lang/Class;
            invokevirtual java.lang.Class.getPackage:()Ljava/lang/Package;
            invokevirtual java.lang.Package.getName:()Ljava/lang/String;
            ldc "org.graalvm.compiler"
            invokevirtual java.lang.String.startsWith:(Ljava/lang/String;)Z
            ifeq 11
        10: .line 86
            goto 14
        11: .line 88
      StackMap locals: com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck java.lang.Thread[] java.lang.Thread int int java.lang.Thread[]
      StackMap stack:
            aload 2 /* t */
            invokevirtual java.lang.Thread.getName:()Ljava/lang/String;
            invokevirtual java.lang.String.toLowerCase:()Ljava/lang/String;
            ldc "libgraal"
            invokevirtual java.lang.String.contains:(Ljava/lang/CharSequence;)Z
            ifeq 13
        12: .line 90
            goto 14
        13: .line 92
      StackMap locals:
      StackMap stack:
            new java.lang.StringBuilder
            dup
            ldc "An extra thread "
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            aload 2 /* t */
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/Object;)Ljava/lang/StringBuilder;
            ldc " is found after test finished."
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
            invokestatic org.junit.Assert.fail:(Ljava/lang/String;)V
        end local 2 // java.lang.Thread t
        14: .line 81
      StackMap locals: com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck java.lang.Thread[] top int int java.lang.Thread[]
      StackMap stack:
            iinc 3 1
      StackMap locals:
      StackMap stack:
        15: iload 3
            iload 4
            if_icmplt 6
        16: .line 96
            aload 0 /* this */
            getfield com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck.threadIDs:Ljava/util/Set;
            invokeinterface java.util.Set.clear:()V
        17: .line 97
            return
        end local 1 // java.lang.Thread[] threads
        end local 0 // com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0   18     0     this  Lcom/oracle/truffle/tools/chromeinspector/test/EnginesGCedTest$GCCheck;
            2    3     1      ref  Ljava/lang/ref/WeakReference<*>;
            5   18     1  threads  [Ljava/lang/Thread;
            7   14     2        t  Ljava/lang/Thread;

  void addReference(java.lang.Object);
    descriptor: (Ljava/lang/Object;)V
    flags: (0x0000) 
    Code:
      stack=4, locals=2, args_size=2
        start local 0 // com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck this
        start local 1 // java.lang.Object engine
         0: .line 100
            aload 0 /* this */
            getfield com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck.collectibleRefs:Ljava/util/Set;
            new java.lang.ref.WeakReference
            dup
            aload 1 /* engine */
            invokespecial java.lang.ref.WeakReference.<init>:(Ljava/lang/Object;)V
            invokeinterface java.util.Set.add:(Ljava/lang/Object;)Z
            pop
         1: .line 101
            return
        end local 1 // java.lang.Object engine
        end local 0 // com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck this
      LocalVariableTable:
        Start  End  Slot    Name  Signature
            0    2     0    this  Lcom/oracle/truffle/tools/chromeinspector/test/EnginesGCedTest$GCCheck;
            0    2     1  engine  Ljava/lang/Object;
    MethodParameters:
        Name  Flags
      engine  

  private static java.lang.Thread[] findAllThreads();
    descriptor: ()[Ljava/lang/Thread;
    flags: (0x000a) ACC_PRIVATE, ACC_STATIC
    Code:
      stack=2, locals=3, args_size=0
         0: .line 104
            invokestatic java.lang.Thread.currentThread:()Ljava/lang/Thread;
            invokevirtual java.lang.Thread.getThreadGroup:()Ljava/lang/ThreadGroup;
            astore 0 /* threadGroup */
        start local 0 // java.lang.ThreadGroup threadGroup
         1: .line 106
            aload 0 /* threadGroup */
            invokevirtual java.lang.ThreadGroup.activeCount:()I
            istore 1 /* activeThreadCount */
        start local 1 // int activeThreadCount
         2: .line 107
            iload 1 /* activeThreadCount */
            bipush 10
            iadd
            anewarray java.lang.Thread
            astore 2 /* threads */
        start local 2 // java.lang.Thread[] threads
         3: .line 108
            aload 0 /* threadGroup */
            aload 2 /* threads */
            invokevirtual java.lang.ThreadGroup.enumerate:([Ljava/lang/Thread;)I
            pop
         4: .line 109
            aload 2 /* threads */
            areturn
        end local 2 // java.lang.Thread[] threads
        end local 1 // int activeThreadCount
        end local 0 // java.lang.ThreadGroup threadGroup
      LocalVariableTable:
        Start  End  Slot               Name  Signature
            1    5     0        threadGroup  Ljava/lang/ThreadGroup;
            2    5     1  activeThreadCount  I
            3    5     2            threads  [Ljava/lang/Thread;
}
SourceFile: "EnginesGCedTest.java"
NestHost: com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest
InnerClasses:
  final GCCheck = com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest$GCCheck of com.oracle.truffle.tools.chromeinspector.test.EnginesGCedTest