Query a set of resources.

def filter(self, resource_manager, **params):
        """Query a set of resources."""
        m = self.resolve(resource_manager.resource_type)
        client = local_session(self.session_factory).client(m.service)

        enum_op, path, extra_args = m.enum_spec
        if extra_args:
            params.update(extra_args)

        parent_type, parent_key, annotate_parent = m.parent_spec
        parents = self.manager.get_resource_manager(parent_type)
        parent_ids = [p[parents.resource_type.id] for p in parents.resources()]

        # Bail out with no parent ids...
        existing_param = parent_key in params
        if not existing_param and len(parent_ids) == 0:
            return []

        # Handle a query with parent id
        if existing_param:
            return self._invoke_client_enum(client, enum_op, params, path)

        # Have to query separately for each parent's children.
        results = []
        for parent_id in parent_ids:
            merged_params = self.get_parent_parameters(params, parent_id, parent_key)
            subset = self._invoke_client_enum(
                client, enum_op, merged_params, path, retry=self.manager.retry)
            if annotate_parent:
                for r in subset:
                    r[self.parent_key] = parent_id
            if subset and self.capture_parent_id:
                results.extend([(parent_id, s) for s in subset])
            elif subset:
                results.extend(subset)
        return results