This is a helper class to use one given element in an iterator quest.
The possible user pattern is:
//Often there is only one action (Operation + output event), then this aggregation is used.
//It is null if #transitions is given, or if no action exists.
MyType element;
//If more as one action is associated to the entry of the dstState, then this list is used and #transition is null.
List elements;
//...
//Iterable works also for one given element:
Iterable iter = (element !=null ? new IteratorOneElement(element) : elements;
for(Element e : iter) { ....}