[BUGFIX] Throw exception when trying to reflect a non-existing class
Previously the ``ReflectionService`` ignored classes that couldn't be
loaded. It just logged an error and marked the respective class
This leads to weird side effects that are hard to track down.
With this change an exception is thrown during compile time whenever
a class is being reflected that couldn't be loaded.
If a class or file should be skipped during reflection, the
``excludeClasses`` can be used::
Releases: master, 2.3, 2.2, 2.1