Format for datetime is invalid

[wdroste]

Current format:
yyyy-MM-dd'T'HH:mm:ss.sss

Correct format:
yyyy-MM-dd'T'HH:mm:ss.SSS

The 'S' is fraction of a second.

[wdroste]

Also suggestion using the thread-safe version

  private static final DateTimeFormatter DATE_TIME_FORMATTER =
      DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSS");