It should be dead simple to make a planning entity immovable if a boolean field on it is true.
Almost everybody needs this and the movableEntitySelectionFilter=... approach is too much work for something so common.

Instead we want:

@PlanningEntity
private class Shift{
   @PlanningPinned
   private boolean lockedByHuman;

}

Advanced case:

@PlanningEntity
private class Shift{
   @PlanningPinned
   private boolean lockedByHuman;
   @PlanningPinned
   private boolean borrowedByAnotherDepartment;
   @PlanningPinned
   private boolean lockedBecauseItsHistory;

}

Open question: how shall we call that annotation? @PlanningPinned or @PlanningLocked or @PlanningImmovable?