Is there a pattern solution.

This being a restful service a facade pattern is the first obvious choice, This would suggest initial 3 classes behind the facade. These are Account, AssessmentCreator and AssessmentParticipant. I did think of removing the Account class but it would be better to have separate classes for accounts and the assessment creation. Strategy pattern could facilitate the creation and execution of custom built assessments.

Initial Class Diagram

Librarian class has been created because assessmentParticipant has a different view of the assessment to the assessment creator. I could just do this in the AssessmentParticipant class but I anticipate that the will be other functions the assessmentPaticipant class will be responsible for. In keeping with the strategy pattern the assessments are interfaces that that are implemented with a set if of IassessmentComponents.