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

224		 *225		 * @since 4.9.0226		 *227		 * @param int|null   $main_site_id If a positive integer is returned, it is interpreted as the main site ID.228		 * @param WP_Network $network      The network object for which the main site was detected.229		 */230		$main_site_id = (int) apply_filters( 'pre_get_main_site_id', null, $this );231 232		if ( 0 < $main_site_id ) {233			return $main_site_id;234		}235 236		if ( 0 < (int) $this->blog_id ) {