Do not add @timestamp if it is already in dst. #3562

[slamp]

PR to correct issue: https://github.com/elastic/logstash/issues/3562

This avoids building up a huge array of timestamps and taking only the first one later on in function merge().

[jsvd]

Would you consider adding a test showing the expected behaviour regarding @timestamp? For examples of tests you can check https://github.com/logstash-plugins/logstash-filter-multiline/blob/master/spec/filters/multiline_spec.rb#L119-L133

[slamp]

1/ I'm not sure putting the test after will have the same behavior as this is a recursive function.

2/ I will try to add a test (I will have to learn a little more ruby first)

3/ I'm not able to sign the "CLA". I got a 404 when clicking "details" < https://github.com/logstash-plugins/logstash-filter-multiline/blob/master/CONTRIBUTING.md#contribution-steps >

[purbon]

Thanks a lot for your contribution @slamp , in order to move forward with your PR is going to be necessary to sign the CLA agreement, you can find more information at https://www.elastic.co/contributor-agreement (this is the correct link!)

On the other side, it would be super nice if you can add test for this change. Don't hesitate to ask any question regarding you might have, more than looking forward to help.

[elasticsearch-release]

Jenkins standing by to test this. If you aren't a maintainer, you can ignore this comment. Someone with commit access, please review this and clear it for Jenkins to run; then say 'jenkins, test it'.

[slamp]

I signed the CLA. I did not have time to add a test.