Documented time zone handling does not match Joda-Time's time zone handling

[kesslerm]

Description:

The documentation shows 3 different possible values for the time zone offset: Z, ZZ, and ZZZ. This is in line with the way Java's DateTimeFormat handles time zone offsets. However, Joda-Time (which this plugin still uses) knows only the single Z character.

URL:

https://www.elastic.co/guide/en/logstash/current/plugins-filters-date.html
https://github.com/JodaOrg/joda-time/blob/master/src/main/java/org/joda/time/format/DateTimeFormat.java