ClassHierarchyResolver throws java.lang.IllegalArgumentException with message "Could not resolve class xyz..." when class hierarchy resolution fails to get relevant ClassHierarchyInfo about given class or interface.
From the user perspective there is missing pointer how to resolve such situation. Therefor it would be nice to implement following improvements:

A better message describing more precisely what happened and point to an improved documentation with hints to resolve it.

A specific exception type (subtype of java.lang.IllegalArgumentException) may help to handle this specific situations in a user code.

ClassHierarchyInfo about the class actually built should be implicitly known to the class hierarchy resolution process to avoid errors related to its own resolution. We suppose to already know if thisClass is an interface and its superClass, when the class hierarchy resolution is in process.