code: public @Nonnull SetType getBlockingThreads() {
          final ThreadType blocking = getBlockingThread();
          if (blocking == null) return runtime.getEmptyThreadSet();
  
          return runtime.getThreadSet(Collections.singleton(blocking));
      }
docs: Get threads holding lock this thread is trying to acquire.
  
  @return {@link ThreadSet} that contains blocked thread or empty set if this thread does not hold any lock.