If an annotation like this is used:
the generated XML will contain only the first scope (i.e. request)
The problem is https://github.com/apache/felix/blob/trunk/scrplugin/annotations/src/main/java/org/apache/felix/scrplugin/processing/SlingAnnotationProcessor.java#L191. That can only deal with single values.
Rather it should use the helper method generateStringPropertyDescriptor, like it is done for all the multivalue fields of the annotation @SlingServlet.