https://openjdk.java.net/ 
public interface sun.management.HotspotThreadMBean
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: sun.management.HotspotThreadMBean
  super_class: java.lang.Object
{
  public abstract int getInternalThreadCount();
    descriptor: ()I
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT

  public abstract java.util.Map<java.lang.String, java.lang.Long> getInternalThreadCpuTimes();
    descriptor: ()Ljava/util/Map;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Signature: ()Ljava/util/Map<Ljava/lang/String;Ljava/lang/Long;>;

  public abstract java.util.List<sun.management.counter.Counter> getInternalThreadingCounters();
    descriptor: ()Ljava/util/List;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Signature: ()Ljava/util/List<Lsun/management/counter/Counter;>;
}
SourceFile: "HotspotThreadMBean.java"