@Override
  public int tryEnumerate(@Nullable String value) throws IOException {
    if (value == null) {
      return NULL_ID;
    }
    int valueHash = hashOf(value);
    synchronized (valueHashLock) {
      Int2IntMultimap valueHashToId = valueHashToId();
      return lookupValue(valueHashToId, value, valueHash);
    }
  }
@Override
  public int tryEnumerate(@Nullable String value)