Flaky tests

[sormuras]

Here's a set of tests that sometimes pass and sometimes fail (mostly on CI systems):

• https://github.com/sormuras/silk/runs/733638112?check_suite_focus=true#step:5:590
  MethodSource [className = 'se.jbee.inject.event.TestTTLExceptionHandingComputeEvents', methodName = 'thatTimeoutExceptionIsThrownIfHandlerMethodThrowsSuperclassException', methodParameterTypes = ''] => java.lang.AssertionError: should throw TimeoutException

[jbee]

I am aware. We might just @ignore them for the moment and put a comment to write a test that cannot time out instead. I did not want to put in too much time for the events as I have plans to rework its core at some point.