CMS: Unknown GCCause

[AlinaHovakimyan]

GCCause comes Unknown for all the events except CMSRemark. Handling seems to be missing because when publishing the events the cause is being set to "Unknown".

[dsgrieve]

We'll need a gc log for this one, too. For most of the CMS events, the cause is unknown because it just isn't in the log. We do have tests for this.

[AlinaHovakimyan]

@dsgrieve this is the log file used: cms_gen.log

For example in line 22, gc reason is "CMS Initial Mark", but it comes as unknown in the event. Also I see a lot of "Allocation Failure"s.