code: public static BigDecimal add(final BigDecimal start, final BigDecimal... values) {
          BigDecimal total = start != null ? start : BigDecimal.ZERO;
          if (values != null) {
              for (final BigDecimal v : values) {
                  total = doAdd(total, v);
              }
          }
          return total;
      }
docs: Add n BigDecimal safely (i.e. handles nulls)
  @param start initial BigDecimal
  @param values series of BigDecimals can be null/empty
  @return the sum of the n non null BigDecimals