The short version is that RuleAdapter.mapFactsToProperties would hit an exception trying to hard-cast a genericized parameter type to Class<?> when it's really WildCardType or TypeVariable. The problem is caused by a @Given with no name that is a Collection type of a wildcarded parameter. e.g. Set<?> or Set<? extends Foo> or List<T>
I made a PR with a fix that also describes the issue.
https://github.com/deliveredtechnologies/rulebook/pull/173
The short version is that
RuleAdapter.mapFactsToPropertieswould hit an exception trying to hard-cast a genericized parameter type toClass<?>when it's reallyWildCardTypeorTypeVariable. The problem is caused by a@Givenwith no name that is a Collection type of a wildcarded parameter. e.g.Set<?>orSet<? extends Foo>orList<T>