Solver: Solving two divergences with two Solvers on different properties should not be considered a conflict.

Use case:
  * Property 1: Accept Solver on 'title'.
  * Property 2: Adopt Solver on 'start_date'.
=> This was not implemented and raising an error as AppropriateUIMessage(whatever) is not defined.

movement_dict:
  {<Simulation Movement at /erp5/portal_simulation/133959/1/1/1>: {<Solver Type at /erp5/portal_solvers/Adopt Solver>: [(('tested_property_list',
                                                                                                                          ['title']),)],
                                                                   <Solver Type at /erp5/portal_solvers/Accept Solver>: [(('tested_property_list',
                                                                                                                           ['stop_date']),),
                                                                                                                         (('tested_property_list',
                                                                                                                           ['start_date']),)]}}
self: <Solver Type at /erp5/portal_solvers/Adopt Solver>
  self.getTestedProperty() is None
solver: <Solver Type at /erp5/portal_solvers/Accept Solver>
  solver.getTestedProperty() is None