code: public static String constructFilePath(String oldFilePath, long recordCounts) {
      return new Path(new Path(oldFilePath).getParent(), Files.getNameWithoutExtension(oldFilePath).toString() + SEPARATOR
          + recordCounts + SEPARATOR + Files.getFileExtension(oldFilePath)).toString();
    }
docs: Construct a new file path by appending record count to the filename of the given file path, separated by SEPARATOR.
  For example, given path: "/a/b/c/file.avro" and record count: 123,
  the new path returned will be: "/a/b/c/file.123.avro"