Ignore HST bean classes that are do not have a public access modifier

From Wouter Danes:

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It's possible to annotate abstract classes with @Node. This means you can get an InstantiationException when you try to "object convert" a node of that type. In my opinion, Hippo shouldn't map a node to an abstract class, because it doesn't make sense. In my opinion the annotation-scanner should log an error and ignore the @Node annotated abstract class.
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Thanks for the suggestion!