Clear cache for resource path.
        :param path: str
        :param filter_name: str or None

def clear_cache(self, path, filter_name=None):
        """
        Clear cache for resource path.
        :param path: str
        :param filter_name: str or None
        """
        if filter_name:
            self._adapter.remove_cached_item('%s/%s' % (filter_name, path))
        else:
            for filter_name in self._filter_sets:
                self._adapter.remove_cached_item('%s/%s' % (filter_name, path))