code: protected static Profile stop()
    {
      Root result = PROFILER_STEPS.get();
      PROFILER_STEPS.remove();
      return result != null ? result.popData() : null;
    }
docs: Stop the profiler.
  <p>
  This should be called in a {@code finally} block to avoid leaving data on
  the thread.
  
  @return The profiling data.