Switch FastDateFormat to DateTimeFormatter

[philsttr]

Switch usage of FastDateFormat to DateTimeFormatter

Remove dependency on apache commons-lang3 (since FastDateFormat was the only thing being used).

Switch default timestamp format to DateTimeFormatter.ISO_OFFSET_DATE_TIME

Added the ability to specify DateTimeFormatter constant names as patterns.

This change is NOT fully backwards compatible, since:

• the default timestamp pattern changed to DateTimeFormatter.ISO_OFFSET_DATE_TIME
• the pattern strings supported by DateTimeFormatter are not exactly the same as those supported previously by FastDateFormat

When this PR is merged, the major version will need to be bumped due to the backwards incompatibilities.
Therefore, holding off on merging this PR until ready for a new major release.

[mfriess2]

We have the problem with the randomly sorted log messages, too (if their millisecond-precision-timestamps are the same).
Are there any plans on releasing this patch soon?

ELK released the fix with 7.0? elastic/elasticsearch#10005
However, Logback still seems to be unfinished, too? https://jira.qos.ch/browse/LOGBACK-1374

[philsttr]

Hi @mfriess2 , this change to logstash-logback-encoder to switch to DateTimeFormatter, by itself, will not help your situation. Higher precision timestamps will need to be supported in logback (via the logback issue you mentioned) before logstash-logback-encoder can take advantage of them. Since the pace of development of logback is extremely slow, and this would likely be a major change to logback, I am not expecting it to be implemented in logback any time soon.