[plotterparameter] first plotter selected instead of blank selection and schema validation is wrong (having 1 plotter selected is a requirement)
As in #154 (closed) and fixed in my MR !23 (merged) we have the same issue for the plotterparameter component: The selector by default shows the first available plotter as selected, but it should really show a "blank" selection, prompting the user to choose a plotter. It tricks the user to believe that he has selected something BUT in the json file there's no plotter selected.
The plotterparameter believes it is valid even without any plotter. This needs to be fixed