@Override
  public String getCurrentName() throws IOException {
    if (state() == AbstractBsonReader.State.NAME) {
      return nextFieldName();
    } else if (state() == AbstractBsonReader.State.VALUE) {
      return reader.getCurrentName();
    }

    return null;
  }
The ObjectCodec used to parse the Bson object(s)
mongo/src/org/immutables/mongo/bson4jackson/BsonParser.java