Add TCP keepalive to Logstash output plugins

[DonDallas71]

Would it be possible to add support for TCP keepalive in some of the output plugins by default?

I found that the tcp input plugin supports keepalive
/usr/share/logstash/vendor/bundle/jruby/3.1.0/gems/logstash-input-tcp-6.4.3-java/lib/logstash/inputs/tcp.rb

However I need this on some output plugins
/usr/share/logstash/vendor/bundle/jruby/3.1.0/gems/logstash-output-syslog-3.0.5/lib/logstash/outputs/syslog.rb
/usr/share/logstash/vendor/bundle/jruby/3.1.0/gems/logstash-output-tcp-6.2.1/lib/logstash/outputs/tcp.rb

Currently I am manually duplicating the keepalive settings from the tcp-input plugin over to the tcp-output and syslog-output plugins to enable this feature every time I update logstash. Would be nice if this were baked in so it could be easily turned on in the config.

[robbavey]

@DonDallas71 As you have already implemented this locally, would you be willing to submit PRs for the syslog and tcp plugins?