'Returns Ext Resources.'

@classmethod
def get_resources(cls):

    special_mappings = {'policies': 'policy'}
    plural_mappings = resource_helper.build_plural_mappings(special_mappings, itertools.chain(RESOURCE_ATTRIBUTE_MAP, SUB_RESOURCE_ATTRIBUTE_MAP))
    resources = resource_helper.build_resource_info(plural_mappings, RESOURCE_ATTRIBUTE_MAP, constants.QOS, translate_name=True, allow_bulk=True)
    plugin = directory.get_plugin(constants.QOS)
    for collection_name in SUB_RESOURCE_ATTRIBUTE_MAP:
        resource_name = collection_name[:(-1)]
        parent = SUB_RESOURCE_ATTRIBUTE_MAP[collection_name].get('parent')
        params = SUB_RESOURCE_ATTRIBUTE_MAP[collection_name].get('parameters')
        controller = base.create_resource(collection_name, resource_name, plugin, params, allow_bulk=True, parent=parent, allow_pagination=True, allow_sorting=True)
        resource = extensions.ResourceExtension(collection_name, controller, parent, path_prefix=QOS_PREFIX, attr_map=params)
        resources.append(resource)
    return resources
