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

      int id = writeString(value, valuesLog);

      valueHashToId.put(valueHash, id);
      return id;
    }
  }
@Override
  public int enumerate(@Nullable String value)