code: public static Integer safeAdd(final Integer v1, final Integer v2) {
          Integer total = v1;
          if (v1 != null && v2 != null) {
              total = v1 + v2;
          } else if (v2 != null) {
              total = v2;
          }
          return total;
      }
docs: Add 2 BigDecimal safely (i.e. handles nulls)