code: public final B requestStartTime(long requestStartTimeNanos, long requestStartTimeMicros) {
          this.requestStartTimeNanos = requestStartTimeNanos;
          this.requestStartTimeMicros = requestStartTimeMicros;
          requestStartTimeSet = true;
          return self();
      }
docs: Sets the request start time of the request.
  
  @param requestStartTimeNanos the {@link System#nanoTime()} value when the request started.
  @param requestStartTimeMicros the number of microseconds since the epoch when the request started.