Unify the emptyOrAlreadyExists in several aspects
The method emptyOrAlreadyExists is implemented in several classes.
Most of the implementation is identical for all classes. Differences are:
- string shown in the error message: this can either be unified as “Signal name is not valid” and “A Signal with this name already exists.” or te string can be passed as arguments
- the local variable from which the getSignals() is called
The latter requires that all the types of those variables (at least MooNSolutionRequirementSpecification, ModeSpecification, FunctionalSpecification) extend ISignalsContainer.
This requires modifing the model so probably also creating a migrator (not sure if this is really the case)
(from redmine: issue id 3468, created on 2018-07-03)