MkIssueEvents.java:139-144: Make it possible to set the...

The puzzle `1063-0509ffcb` from #1063 has to be resolved:

https://github.com/jcabi/jcabi-github/blob/5c55c3b06922e67860702945eb86e02d7b5f09ef/src/main/java/com/jcabi/github/mock/MkIssueEvents.java#L139-L144

The puzzle was created by Chris Rebert on 15-Apr-15.

Estimate: 30 minutes,

If you have any technical questions, don't ask me, submit new tickets instead. The task will be \"done\" when the problem is fixed and the text of the puzzle is _removed_ from the source code. Here is more about [PDD](http://www.yegor256.com/2009/03/04/pdd.html) and [about me](http://www.yegor256.com/2017/04/05/pdd-in-action.html).