SolutionState does only offer optimal but not valid or satisfiable
The SolutionState of an ExplorationSolution offers only an optimal option if the DSE was successful. However, using e.g. the non-opimizing z3 solver, only a valid or satisfiable state would be needed as the model returned by the solver specifically is not optimal.
(from redmine: issue id 3360, created on 2018-03-29, closed on 2019-01-25)