Nice to hear things are starting to work out!
As you already guessed, this is by design. These helper classes are internal implementation artifacts of the SessionBindingConversationManager. By making them package private, we keep them out of the user visible API. This gives us more freedom refactoring these classes since we don't have to worry about breaking user applications.Now comes my question. Why not make these classes public? If I can extend the SessionBindingConversationManager why not make its helper classes visible?