Plan plan = Optional.ofNullable(planRepository.findOne(planId)).orElseThrow(
    () -> new PlanNotFoundException(planId, PlanNotFoundException.PlanNotFoundExceptionCode.PLAN_NOT_FOUND_FOR_ID));

if (!planRepository.exists(planId))
    throw new PlanNotFoundException(planId, PlanNotFoundException.PlanNotFoundExceptionCode.PLAN_NOT_FOUND_FOR_ID);