output: #fixed code
                                  private void commonInitialization(IntVar[] list, int[] weights, int sum) {
  
          queueIndex = 4;
  
          assert (list.length == weights.length) : "\nLength of two vectors different in SumWeightDom";
  
          numberArgs = (short) (list.length + 1);
  
          numberId = idNumber.incrementAndGet();
  
          this.sum = sum;
  
          HashMap<IntVar, Integer> parameters = new HashMap<IntVar, Integer>();
  
          for (int i = 0; i < list.length; i++) {
  
              assert (list[i] != null) : i + "-th element of list in SumWeightDom constraint is null";
  
              if (weights[i] == 0)
                  continue;
  
              if (parameters.get(list[i]) != null) {
                  // variable ordered in the scope of the Sum Weight constraint.
                  Integer coeff = parameters.get(list[i]);
                  Integer sumOfCoeff = coeff + weights[i];
                  parameters.put(list[i], sumOfCoeff);
              } else
                  parameters.put(list[i], weights[i]);
  
          }
  
          this.list = new IntVar[parameters.size()];
          this.weights = new int[parameters.size()];
  
          int i = 0;
          for (Map.Entry<IntVar,Integer> e : parameters.entrySet()) {
  	  this.list[i] = e.getKey();
              this.weights[i] = e.getValue();
              i++;
          }
  
          checkForOverflow();
      }
input: #vulnerable code 
                                  private void commonInitialization(IntVar[] list, int[] weights, int sum) {
  
          queueIndex = 4;
  
          assert (list.length == weights.length) : "\nLength of two vectors different in SumWeightDom";
  
          numberArgs = (short) (list.length + 1);
  
          numberId = idNumber.incrementAndGet();
  
          this.sum = sum;
  
          HashMap<IntVar, Integer> parameters = new HashMap<IntVar, Integer>();
  
          for (int i = 0; i < list.length; i++) {
  
              assert (list[i] != null) : i + "-th element of list in SumWeightDom constraint is null";
  
              if (weights[i] == 0)
                  continue;
  
              if (parameters.get(list[i]) != null) {
                  // variable ordered in the scope of the Sum Weight constraint.
                  Integer coeff = parameters.get(list[i]);
                  Integer sumOfCoeff = coeff + weights[i];
                  parameters.put(list[i], sumOfCoeff);
              } else
                  parameters.put(list[i], weights[i]);
  
          }
  
          this.list = new IntVar[parameters.size()];
          this.weights = new int[parameters.size()];
  
          int i = 0;
          for (IntVar var : parameters.keySet()) {
              this.list[i] = var;
              this.weights[i] = parameters.get(var);
              i++;
          }
  
          checkForOverflow();
      } 
                              #location 38 
                              #vulnerability type NULL_DEREFERENCE