This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
public static interface PageActionManager.ActionSourceTransformer
for some widgets, a subcomponent will fire the event, but a parent widget has
the action attached to it. This is typically the case for action on a table
cell, where the action is declared on the whole table. This interface allows
to transform the local widget to the parent widget that should get the action
(Note: there should be a way in the parent widget to remember which lower
level widget was selected