code: public static BigDecimal inverse(final BigDecimal value, final int scale, final int rounding) {
          if (isNotZero(value)) {
              return BigDecimal.ONE.divide(value, scale, rounding);
          }
          return null;
      }
docs: Return the inverse of value if not null or zero, using scale.
  @param value the nullable BigDecimal
  @param scale scale for the result if value is not null
  @param rounding the rounding (see BigDecimal)
  @return 1 / value (if not null of zero)