code: public function getMaximumRemainingTime()
      {
          if (($timeLimits = $this->getSource()->getTimeLimits()) !== null && ($maxTime = $timeLimits->getMaxTime()) !== null) {
              return $this->getRemainingTimeFrom($maxTime);
          }
          return false;
      }
docs: Get the time remaining to be spent by the candidate on the source of the time
  constraint. Please note that this method will never return negative durations.
  
  @return Duration A Duration object or null if there is no maxTime constraint running for the source of the time constraint.