[logback-user] ThrowableProxy and instanceof in EventEvaluator

In an event evaluator called in an option of an "ex" formatting specifier I would use a "throwable instanceof example" expression. This is the same as in Example 5.3 in the documentation, which also uses instanceof. This doesn't work because the throwable object is not a Throwable but a ThrowableProxy. Again, at another place, in the table at the beginning of the "Evaluator Filters taking Java Expressions" section in chapter Filters it is shown that the type of throwable is Throwable (annd not ThrowableProxy). Somehow I still get a ThrowableProxy instead of Throwable.