public boolean decRefCount(){
  int rc=refCountUpdater.decrementAndGet(this);
  if (rc < 0) {
    throw new IllegalStateException("rc=" + rc);
  }
  return rc == 0;
}

public boolean decRefCount ( ) { int rc = refCountUpdater . decrementAndGet ( this ) ; if ( rc < 0 ) { throw new IllegalStateException ( "rc=" + rc ) ; } return rc == 0 ; }
returns true if refcount goes to 0 .
