code: function _getHandlerAttribute (member, handlerAttributeArray) {
          var attribute;
          if (1 !== handlerAttributeArray.length()) {
              gpf.Error.htmlHandlerMultiplicityError({
                  member: member
              });
          }
          attribute = handlerAttributeArray.get(0);
          if (!(attribute instanceof _HtmEvent)) {
              return attribute;
          }
          return null;
      }
docs: endregion region HTML event handlers mappers through attributes