code: public MockResponse throttleBody(int bytesPerPeriod, long period, TimeUnit unit) {
          this.throttleBytesPerPeriod = bytesPerPeriod;
          this.throttlePeriod = period;
          this.throttleUnit = unit;
          return this;
      }
docs: Throttles the response body writer to sleep for the given period after each
  series of {@code bytesPerPeriod} bytes are written. Use this to simulate
  network behavior.