able via the JSON API.
		 *
		 * @module sync
		 *
		 * @since 5.7.0
		 *
		 * @param array The default list of comment meta data keys.
		 */
		return apply_filters( 'jetpack_sync_comment_meta_whitelist', self::$comment_meta_whitelist );
	}

	/**
	 * Default theme support whitelist.
	 *
	 * @todo move this to server? - these are theme support values
	 * that should be synced as jetpack_current_theme_supports_foo option values
	 *
	 * @var array Default theme support whitelist.
	 */
	public static $default_theme_support_whitelist = array(
		'post-thumbnails',
		'post-formats',
		'custom-header',
		'custom-background',
		'custom-logo',
		'menus',
		'automatic-feed-links',
		'align-wide',
		'wp-block-styles',
		'responsive-embeds',
		'disable-custom-gradients',
		'disable-custom-font-sizes',
		'disable-custom-colors',
		'dark-editor-style',
		'customize-selective-refresh-widgets',
		'widgets',
		'html5',
		'title-tag',
		'jetpack-social-menu',
		'jetpack-responsive-videos',
		'infinite-scroll',
		'site-logo',
		'editor-color-palette',
		'editor-gradient-presets',
		'editor-font-sizes',
		'editor-styles',
		'editor-style', // deprecated.
	);

	/**
	 * Is an option whitelisted?
	 *
	 * @param string $option Option name.
	 * @return bool If option is on the whitelist.
	 */
	public static function is_whitelisted_option( $option ) {
		$whitelisted_options = self::get_options_whitelist();
		foreach ( $whitelisted_options as $whitelisted_option ) {
			if ( '/' === $whitelisted_option[0] && preg_match( $whitelisted_option, $option ) ) {
				return true;
			} elseif ( $whitelisted_option === $option ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Default whitelist of capabilities to sync.
	 *
	 * @var array Array of WordPress capabilities.
	 */
	public static $default_capabilities_whitelist = array(
		'switch_themes',
		'edit_themes',
		'edit_theme_options',
		'install_themes',
		'activate_plugins',
		'edit_plugins',
		'install_plugins',
		'edit_users',
		'edit_files',
		'manage_options',
		'moderate_comments',
		'manage_categories',
		'manage_links',
		'upload_files',
		'import',
		'unfiltered_html',
		'edit_posts',
		'edit_others_posts',
		'edit_published_posts',
		'publish_posts',
		'edit_pages',
		'read',
		'publish_pages',
		'edit_others_pages',
		'edit_published_pages',
		'delete_pages',
		'delete_others_pages',
		'delete_published_pages',
		'delete_posts',
		'delete_others_posts',
		'delete_published_posts',
		'delete_private_posts',
		'edit_private_posts',
		'read_private_posts',
		'delete_private_pages',
		'edit_private_pages',
		'read_private_pages',
		'delete_users',
		'create_users',
		'unfiltered_upload',
		'edit_dashboard',
		'customize',
		'delete_site',
		'update_plugins',
		'delete_plugins',
		'update_themes',
		'update_core',
		'list_users',
		'remove_users',
		'add_users',
		'promote_users',
		'delete_themes',
		'export',
		'upload_plugins',
		'upload_themes',
	);

	/**
	 * Get default capabilities whitelist.
	 *
	 * @return array
	 */
	public static function get_capabilities_whitelist() {
		/**
		 * Filter the list of capabilities that we care about
		 *
		 * @module sync
		 *
		 * @since 5.5.0
		 *
		 * @param array The default list of capabilities.
		 */
		return apply_filters( 'jetpack_sync_capabilities_whitelist', self::$default_capabilities_whitelist );
	}

	/**
	 * Get max execution sync time.
	 *
	 * @return float Number of seconds.
	 */
	public static function get_max_sync_execution_time() {
		$max_exec_time = (int) ini_get( 'max_execution_time' );
		if ( 0 === $max_exec_time ) {
			// 0 actually means "unlimited", but let's not treat it that way.
			$max_exec_time = 60;
		}
		return floor( $max_exec_time / 3 );
	}

	/**
	 * Get default for a given setting.
	 *
	 * @param string $setting Setting to get.
	 * @return mixed Value will be a string, int, array, based on the particular setting requested.
	 */
	public static function get_default_setting( $setting ) {
		$default_name = "default_$setting"; // e.g. default_dequeue_max_bytes.
		return self::$$default_name;
	}

	/**
	 * Default list of network options.
	 *
	 * @var array network options
	 */
	public static $default_network_options_whitelist = array(
		'site_name',
		'jetpack_protect_key',
		'jetpack_protect_global_whitelist',
		'active_sitewide_plugins',
		'auto_update_plugins', // WordPress 5.5+ auto-updates.
	);

	/**
	 * A mapping of known importers to friendly names.
	 *
	 * Keys are the class name of the known importer.
	 * Values are the friendly name.
	 *
	 * @since 7.3.0
	 *
	 * @var array
	 */
	public static $default_known_importers = array(
		'Blogger_Importer'     => 'blogger',
		'LJ_API_Import'        => 'livejournal',
		'MT_Import'            => 'mt',
		'RSS_Import'           => 'rss',
		'WC_Tax_Rate_Importer' => 'woo-tax-rate',
		'WP_Import'            => 'wordpress',
	);

	/**
	 * Returns a list of known importers.
	 *
	 * @since 7.3.0
	 *
	 * @return array Known importers with importer class names as keys and friendly names as values.
	 */
	public static function get_known_importers() {
		/**
		 * Filter the list of known importers.
		 *
		 * @module sync
		 *
		 * @since 7.3.0
		 *
		 * @param array The default list of known importers.
		 */
		return apply_filters( 'jetpack_sync_known_importers', self::$default_known_importers );
	}

	/**
	 * Whether this is a system with a multiple networks.
	 * We currently need this static wrapper because we statically define our default list of callables.
	 *
	 * @since 7.6.0
	 *
	 * @uses Automattic\Jetpack\Status::is_multi_network
	 *
	 * @return boolean
	 */
	public static function is_multi_network() {
		$status = new Status();
		return $status->is_multi_network();
	}

	/**
	 * Default bytes to dequeue.
	 *
	 * @var int Bytes.
	 */
	public static $default_dequeue_max_bytes = 500000; // very conservative value, 1/2 MB.

	/**
	 * Default upload bytes.
	 *
	 * This value is a little bigger than the upload limit to account for serialization.
	 *
	 * @var int Bytes.
	 */
	public static $default_upload_max_bytes = 600000;

	/**
	 * Default number of rows uploaded.
	 *
	 * @var int Number of rows.
	 */
	public static $default_upload_max_rows = 500;

	/**
	 * Default sync wait time.
	 *
	 * @var int Number of seconds.
	 */
	public static $default_sync_wait_time = 10; // seconds, between syncs.

	/**
	 * Only wait before next send if the current send took more than this number of seconds.
	 *
	 * @var int Number of seconds.
	 */
	public static $default_sync_wait_threshold = 10;

	/**
	 * Default wait between attempting to continue a full sync via requests.
	 *
	 * @var int Number of seconds.
	 */
	public static $default_enqueue_wait_time = 1;

	/**
	 * Maximum queue size.
	 *
	 * Each item is represented with a new row in the wp_options table.
	 *
	 * @var int Number of queue items.
	 */
	public static $default_max_queue_size = 5000;

	/**
	 * Default maximum lag allowed in the queue.
	 *
	 * @var int Number of seconds
	 */
	public static $default_max_queue_lag = 7200; // 2 hours.

	/**
	 * Default for default writes per sec.
	 *
	 * @var int Rows per second.
	 */
	public static $default_queue_max_writes_sec = 100; // 100 rows a second.

	/**
	 * Default for post types blacklist.
	 *
	 * @var array Empty array.
	 */
	public static $default_post_types_blacklist = array();

	/**
	 * Default for taxonomies blacklist.
	 *
	 * @var array Empty array.
	 */
	public static $default_taxonomies_blacklist = array();

	/**
	 * Default for taxonomies whitelist.
	 *
	 * @var array Empty array.
	 */
	public static $default_taxonomy_whitelist = array();

	/**
	 * Default for post meta whitelist.
	 *
	 * @var array Empty array.
	 */
	public static $default_post_meta_whitelist = array();

	/**
	 * Default for comment meta whitelist.
	 *
	 * @var array Empty array.
	 */
	public static $default_comment_meta_whitelist = array();

	/**
	 * Default for disabling sync across the site.
	 *
	 * @var int Bool-ish. Default to 0.
	 */
	public static $default_disable = 0; // completely disable sending data to wpcom.

	/**
	 * Default for disabling sync across the entire network on multisite.
	 *
	 * @var int Bool-ish. Default 0.
	 */
	public static $default_network_disable = 0;

	/**
	 * Default for disabling checksums.
	 *
	 * @var int Bool-ish. Default 0.
	 */
	public static $default_checksum_disable = 0;

	/**
	 * Should Sync use cron?
	 *
	 * @var int Bool-ish value. Default 1.
	 */
	public static $default_sync_via_cron = 1;

	/**
	 * Default if Sync should render content.
	 *
	 * @var int Bool-ish value. Default is 0.
	 */
	public static $default_render_filtered_content = 0;

	/**
	 * Default number of items to enqueue at a time when running full sync.
	 *
	 * @var int Number of items.
	 */
	public static $default_max_enqueue_full_sync = 100;

	/**
	 * Default for maximum queue size during a full sync.
	 *
	 * Each item will represent a value in the wp_options table.
	 *
	 * @var int Number of items.
	 */
	public static $default_max_queue_size_full_sync = 1000; // max number of total items in the full sync queue.

	/**
	 * Default max time for sending in immediate mode.
	 *
	 * @var float Number of Seconds
	 */
	public static $default_full_sync_send_duration = 9;

	/**
	 * Defaul for time between syncing callables.
	 *
	 * @var int Number of seconds.
	 */
	public static $default_sync_callables_wait_time = MINUTE_IN_SECONDS; // seconds before sending callables again.

	/**
	 * Default for time between syncing constants.
	 *
	 * @var int Number of seconds.
	 */
	public static $default_sync_constants_wait_time = HOUR_IN_SECONDS; // seconds before sending constants again.
	/**
	 * Default for sync queue lock timeout time.
	 *
	 * @var int Number of seconds.
	 */
	public static $default_sync_queue_lock_timeout = 120; // 2 minutes.

	/**
	 * Default for cron sync time limit.
	 *
	 * @var int Number of seconds.
	 */
	public static $default_cron_sync_time_limit = 4 * MINUTE_IN_SECONDS;

	/**
	 * Default for number of term relationship items sent in an full sync item.
	 *
	 * @var int Number of items.
	 */
	public static $default_term_relationships_full_sync_item_size = 100;

	/**
	 * Default for enabling incremental sync.
	 *
	 * @var int 1 for true.
	 */
	public static $default_sync_sender_enabled = 1; // Should send incremental sync items.

	/**
	 * Default for enabling Full Sync.
	 *
	 * @var int 1 for true.
	 */
	public static $default_full_sync_sender_enabled = 1; // Should send full sync items.

	/**
	 * Default Full Sync config
	 *
	 * @var array list of module names.
	 */
	public static $default_full_sync_config = array(
		'constants'          => 1,
		'functions'          => 1,
		'options'            => 1,
		'updates'            => 1,
		'themes'             => 1,
		'users'              => 1,
		'terms'              => 1,
		'posts'              => 1,
		'comments'           => 1,
		'term_relationships' => 1,
	);

	/**
	 * Default Full Sync max objects to send on a single request.
	 *
	 * @var array list of module => max.
	 */
	public static $default_full_sync_limits = array(
		'users'              => array(
			'chunk_size' => 100,
			'max_chunks' => 10,
		),
		'terms'              => array(
			'chunk_size' => 1000,
			'max_chunks' => 10,
		),
		'posts'              => array(
			'chunk_size' => 100,
			'max_chunks' => 1,
		),
		'comments'           => array(
			'chunk_size' => 100,
			'max_chunks' => 10,
		),
		'term_relationships' => array(
			'chunk_size' => 1000,
			'max_chunks' => 10,
		),
	);

}