code: public BigDecimal getValueAsBigDecimal() {
          String value = (String) $(valueBoxBase.getElement()).val();
          if (value != null && !value.isEmpty()) {
              return new BigDecimal(value);
          } else {
              return null;
          }
      }
docs: Will get the value as a string and return a BigDecimal value
  for long precision instead of Double value.