* @param directory a writable directory.
 * @param valueCount the number of values per cache entry. Must be positive.
 * @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,

                            final Map<String, Object> valueCount = new HashMap<>(2, 1f);
                            valueCount.put("value", e.getKey());
                            valueCount.put("count", e.getValue());
                            return valueCount;
                        }).collect(Collectors.toList()));
                        return fieldMap;

    directory.toOkioPath(),
    maxSize,
  )

  internal val cache =
    DiskLruCache(
      fileSystem = fileSystem,
      directory = directory,
      appVersion = VERSION,
      valueCount = ENTRY_COUNT,
      maxSize = maxSize,
      taskRunner = taskRunner,
    )

  // read and write statistics, all guarded by 'this'.
  internal var writeSuccessCount = 0
  internal var writeAbortCount = 0