I am having the same problems. Reflective code has to be written with extreme care and requires deep knowledge.
This is the same with HHH-8958.

See also:
http://m-m-m.sourceforge.net/apidocs/net/sf/mmm/util/reflect/api/GenericType.html

http://m-m-m.sourceforge.net/apidocs/net/sf/mmm/util/reflect/api/GenericTypeFactory.html#createGenericType%28java.lang.reflect.Type,%20net.sf.mmm.util.reflect.api.GenericType%29

http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/reflect/TypeToken.html