docs: private JsonToken startParsingObjectOrArray() throws IOException {
      JsonToken currentToken = startParsing();
      switch (currentToken) {
        case START_OBJECT:
          currentToken = nextToken();
          Preconditions.checkArgument(
              currentToken == JsonToken.FIELD_NAME || currentToken == JsonToken.END_OBJECT,
              currentToken);
          break;
        case START_ARRAY:
          currentToken = nextToken();
          break;
        default:
          break;
      }
      return currentToken;
    }