Sets shouldEndSession value to null/false/true.

        :param should_end_session: value to show if the session should
            be ended or not.
        :type should_end_session: bool
        :return: response factory with partial response being built and
            access from self.response.
        :rtype: ResponseFactory

def set_should_end_session(self, should_end_session):
        # type: (bool) -> 'ResponseFactory'
        """Sets shouldEndSession value to null/false/true.

        :param should_end_session: value to show if the session should
            be ended or not.
        :type should_end_session: bool
        :return: response factory with partial response being built and
            access from self.response.
        :rtype: ResponseFactory
        """
        if not self.__is_video_app_launch_directive_present():
            self.response.should_end_session = should_end_session
        return self