constructor(logger, maxAge) {
		/** @type {ItemInfo} */
		this.itemInfo = new Map();
		/** @type {(string | undefined)[]} */
		this.requests = [];
		this.requestsTimeout = undefined;
		/** @type {ItemInfo} */
		this.freshContent = new Map();
		/** @type {(undefined | PackContent)[]} */
		this.content = [];
		this.invalid = false;
		this.logger = logger;
		this.maxAge = maxAge;
	}
@param {Logger} logger a logger
@param {number} maxAge max age of cache items