WP_Sitemaps_Registry::add_provider( string $name, WP_Sitemaps_Provider $provider )

	public function add_provider( $name, WP_Sitemaps_Provider $provider ) {
		if ( isset( $this->providers[ $name ] ) ) {
			return false;
		}

		/**
		 * Filters the sitemap provider before it is added.
		 *
		 * @since 5.5.0
		 *
		 * @param WP_Sitemaps_Provider $provider Instance of a WP_Sitemaps_Provider.
		 * @param string               $name     Name of the sitemap provider.
		 */
		$provider = apply_filters( 'wp_sitemaps_add_provider', $provider, $name );
		if ( ! $provider instanceof WP_Sitemaps_Provider ) {
			return false;
		}

		$this->providers[ $name ] = $provider;

		return true;
	}