Which design pattern to use to avoid if/else in validation classes?

I am currently using HibernateConstraintValidator to implement my validations. But my reviewer is not fine with having if/else in code or ! operators. Which design pattern can I use to remove the if/else in my validation logic?

public class SomeValidatorX implements ConstraintValidator<SomeAnnotation, UUID> {

      @Autowired
      SomeRepository someRepository;
   
      @Override
      public boolean isValid(UUID uuid, ConstraintValidationContext context) {

             return !(uuid!=null && someRepository.existsById(uuid)); //The reviewer doesn't want this negation operator
      }
}

And in below code, he doesn't want if/else

public class SomeValidatorY implements ConstraintValidator<SomeAnnotation, SomeClass> {

      @Autowired
      SomeRepository someRepository;
   
      @Override
      public boolean isValid(SomeClass someObject, ConstraintValidationContext context) {
           if(someObject.getFieldA() != null) { //He doesn't want this if statement
                //do some operations
                List<Something> someList = someRepository.findByAAndB(someObject.getFieldA(),B);
                return !someList.isEmpty(); //He doesn't want this ! operator
           }
           return false; // He was not fine with else statement in here as well
      }
}

Side Note: We have to use Domain Driven Design (if it helps)