apply_filters( 'pre_get_main_site_id', int|null $main_site_id, WP_Network $network )

228		 *229		 * @since 4.9.0230		 *231		 * @param int|null   $main_site_id If a positive integer is returned, it is interpreted as the main site ID.232		 * @param WP_Network $network      The network object for which the main site was detected.233		 */234		$main_site_id = (int) apply_filters( 'pre_get_main_site_id', null, $this );235 236		if ( 0 < $main_site_id ) {237			return $main_site_id;238		}239 240		if ( 0 < (int) $this->blog_id ) {