code: @Override
    public Object parse(String value) throws ParseException
    {
      if(value == null || value.isEmpty()) {
        return null;
      }
      return numberFormat.parse(value);
    }
docs: Parse percent from given string value and return it as {@link Number} instance. Given string <code>value</code>
  should have a numeric part and percent sign and should respect this formatter locale. Returns null if
  <code>value</code> argument is null or empty.
  
  @param value percent value.
  @return percent as {@link Number} instance, possible null if <code>value</code> argument is null or empty.
  @throws ParseException if <code>value</code> is not formated as percent.