code: protected void encodeOptionalNativeAttr(final WidgetBuilder wb, final String attrName, final Object value)
                  throws IOException {
          if (value != null) {
              wb.nativeAttr(attrName, value.toString());
          }
      }
docs: Encodes an optional native attribute (unquoted).
  
  @param wb the WidgetBuilder to append to
  @param attrName the attribute name
  @param value the value
  @throws IOException