public function get_collection_params() {

		$params = parent::get_collection_params();

		$params['roles'] = array(
			'description' => __( 'Include only users keys matching matching a specific role. Accepts a single role or a comma separated list of roles.', 'lifterlms' ),
			'type'        => 'array',
			'items'       => array(
				'type' => 'string',
				'enum' => $this->get_enum_roles(),
			),
		);

		return $params;

	}