* @param maxSize the maximum number of bytes this cache should use to store.
 */
class DiskLruCache(
  fileSystem: FileSystem,
  /** Returns the directory where this cache stores its data. */
  val directory: Path,
  private val appVersion: Int,
  internal val valueCount: Int,
  /** Returns the maximum number of bytes that this cache should use to store its data. */
  maxSize: Long,
  /** Used for asynchronous journal rebuilds. */