getContextHash(path, callback) {
		const cache = this._contextHashes.get(path);
		if (cache !== undefined) {
			const resolved = getResolvedHash(cache);
			if (resolved !== undefined)
				return callback(null, /** @type {string} */ (resolved));
			return this._resolveContextHash(cache, callback);
		}
		this.contextHashQueue.add(path, (err, _entry) => {
			if (err) return callback(err);
			const entry = /** @type {ContextHash} */ (_entry);
			const resolved = getResolvedHash(entry);
			if (resolved !== undefined)
				return callback(null, /** @type {string} */ (resolved));
			this._resolveContextHash(entry, callback);
		});
	}
@param {string} path context path
@param {(err?: WebpackError | null, contextHash?: string) => void} callback callback function
@returns {void}