https://openjdk.java.net/ 
class com.sun.tools.jdi.JDWP$ThreadGroupReference
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: com.sun.tools.jdi.JDWP$ThreadGroupReference
  super_class: java.lang.Object
{
  static final int COMMAND_SET;
    descriptor: I
    flags: (0x0018) ACC_STATIC, ACC_FINAL
    ConstantValue: 12

  private void <init>();
    descriptor: ()V
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // com.sun.tools.jdi.JDWP$ThreadGroupReference this
         0: .line 6009
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // com.sun.tools.jdi.JDWP$ThreadGroupReference this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/sun/tools/jdi/JDWP$ThreadGroupReference;
}
SourceFile: "JDWP.java"
NestHost: com.sun.tools.jdi.JDWP
InnerClasses:
  ThreadGroupReference = com.sun.tools.jdi.JDWP$ThreadGroupReference of com.sun.tools.jdi.JDWP
  Children = com.sun.tools.jdi.JDWP$ThreadGroupReference$Children of com.sun.tools.jdi.JDWP$ThreadGroupReference
  Name = com.sun.tools.jdi.JDWP$ThreadGroupReference$Name of com.sun.tools.jdi.JDWP$ThreadGroupReference
  Parent = com.sun.tools.jdi.JDWP$ThreadGroupReference$Parent of com.sun.tools.jdi.JDWP$ThreadGroupReference