WP_REST_Attachments_Controller::get_collection_params()

	public function get_collection_params() {
		$params = parent::get_collection_params();
		$params['status']['default'] = 'inherit';
		$params['status']['items']['enum'] = array( 'inherit', 'private', 'trash' );
		$media_types = $this->get_media_types();

		$params['media_type'] = array(
			'default'           => null,
			'description'       => __( 'Limit result set to attachments of a particular media type.' ),
			'type'              => 'string',
			'enum'              => array_keys( $media_types ),
		);

		$params['mime_type'] = array(
			'default'     => null,
			'description' => __( 'Limit result set to attachments of a particular MIME type.' ),
			'type'        => 'string',
		);

		return $params;
	}