Action constructor Null safety
Constructor sets the ref, in and out? properties
Implementation
Action({required String actionRef, required String actionIn, List<String>? actionOut}) {
assert(actionRef.isNotEmpty && actionIn.isNotEmpty,
"Action must have at least 'in' or 'ref' parameter set to be valid.");
setRef(actionRef);
setIn(actionIn);
if (actionOut != null) setOut(actionOut);
}