output: #fixed code
                                  public PaginationDTO list(Integer page, Integer size) {
  
          PaginationDTO paginationDTO = new PaginationDTO();
  
          Integer totalPage;
  
          Integer totalCount = questionMapper.count();
  
          if (totalCount % size == 0) {
              totalPage = totalCount / size;
          } else {
              totalPage = totalCount / size + 1;
          }
  
          if (page < 1) {
              page = 1;
          }
          if (page > totalPage) {
              page = totalPage;
          }
  
          paginationDTO.setPagination(totalPage, page);
          //size*(page-1)
          Integer offset = size * (page - 1);
          List<Question> questions = questionMapper.list(offset, size);
          List<QuestionDTO> questionDTOList = new ArrayList<>();
  
          for (Question question : questions) {
              User user = userMapper.findById(question.getCreator());
              QuestionDTO questionDTO = new QuestionDTO();
              BeanUtils.copyProperties(question, questionDTO);
              questionDTO.setUser(user);
              questionDTOList.add(questionDTO);
          }
  
          paginationDTO.setQuestions(questionDTOList);
          return paginationDTO;
      }
input: #vulnerable code 
                                  public PaginationDTO list(Integer page, Integer size) {
  
  
          PaginationDTO paginationDTO = new PaginationDTO();
          Integer totalCount = questionMapper.count();
          paginationDTO.setPagination(totalCount, page, size);
  
          if (page < 1) {
              page = 1;
          }
  
          if (page > paginationDTO.getTotalPage()) {
              page = paginationDTO.getTotalPage();
          }
  
          //size*(page-1)
          Integer offset = size * (page - 1);
          List<Question> questions = questionMapper.list(offset, size);
          List<QuestionDTO> questionDTOList = new ArrayList<>();
  
          for (Question question : questions) {
              User user = userMapper.findById(question.getCreator());
              QuestionDTO questionDTO = new QuestionDTO();
              BeanUtils.copyProperties(question, questionDTO);
              questionDTO.setUser(user);
              questionDTOList.add(questionDTO);
          }
  
          paginationDTO.setQuestions(questionDTOList);
          return paginationDTO;
      } 
                              #location 12 
                              #vulnerability type NULL_DEREFERENCE