assertj: Describe actual Throwables when ThrowableAssert fails

Summary

When some Throwable-related assertion fails the actual Throwable that failed the check is not described beyond what actually caused assertion failure (e.g. message mismatch). In non-trivial code when unexpected Exceptions are thrown this makes debugging inconvenient.

Dumping more comprehensive (class, message, stack, perhaps even recursive info about causes) info about the actual Throwable could ease assertion failure investigation.

Relevant message factories (e.g. ShouldHaveMessage) already have access to actual Throwable.

It may be tempting to use util.Throwables.ERROR_DESCRIPTION_EXTRACTOR to describe throwables, but a more powerful mechanism would be appreciated. Providing precise information in case of assertion failure doesn’t seem to be overkill (unlike as in #864)

Error message to improve

• ShouldHaveCause #2872
• ShouldHaveCauseExactlyInstance
• ShouldHaveCauseInstance
• ShouldHaveCauseReference - @weiyilei
• ShouldHaveNoCause
• ShouldHaveNoSuppressedExceptions
• ShouldHaveRootCauseExactlyInstance #2910
• ShouldHaveRootCauseInstance #2910
• ShouldHaveSuppressedException
• ShouldNotContainCharSequence
• ShouldStartWith
• ShouldEndWith

If you are interested in contributing to this issue, select one error message, it will be assigned to you.