* allow in normal conditions. This is enforced by "throttling" incoming requests as needed. For
   * example, we could compute the appropriate throttle time for an incoming request, and make the
   * calling thread wait for that time.
   *
   * The simplest way to maintain a rate of QPS is to keep the timestamp of the last granted

  }

  /**
   * Updates the stable rate of this {@code RateLimiter}, that is, the {@code permitsPerSecond}
   * argument provided in the factory method that constructed the {@code RateLimiter}. Currently
   * throttled threads will <b>not</b> be awakened as a result of this invocation, thus they do not
   * observe the new rate; only subsequent requests will.
   *