(backport: 11.4 for LS7.x) Fixes an issue where events containing non-unicode strings.

[mashhurs]

See origin PR for the details, applying to 11.4.x versions to be available in LS 7.17.x core

[yaauie]

I believe we also need to backport https://github.com/logstash-plugins/logstash-output-elasticsearch/pull/1139 to fix the SSL-related permaloops we are seeing in CI

EDIT: that applies to 11.14.x, not 11.4.x :facepalm:

[yaauie]

Ah, it looks like https://github.com/logstash-plugins/logstash-output-elasticsearch/pull/1137 is relevant backport-to-fix-tests candidate, or the spec/fixtures/test_certs/renew.sh from #1074