anchor.diff:  The ID must never be null and must be unique per class (no need to be globally unique).
   
   This enables the use of multi-threaded solvers (such as Partitioned Search)
  -and makes it easier to implement a real-time planning `ProblemFactChange` by using `ScoreDirector.locateWorkingObject()`.
  +and makes it easier to implement a real-time planning `ProblemFactChange` by using `ScoreDirector.lookUpWorkingObject()`.
   
   Before in `*.java`:
   [source, java]
  
positive.code: ----
  
  
  [.upgrade-recipe-major.upgrade-recipe-public-api]
  === Score rules that change 2 score levels must call `addMultiConstraintMatch()`
  
  A score rule that changes 2 score levels in its RHS,
  must now call `addMultiConstraintMatch()` instead of 2 separate `add*ConstraintMatch()` calls.
  
negative.code: 
  
  [.upgrade-recipe-minor]
  === `Bendable*Score`: method `isFeasible()` fixed
  
  A bendable score with at least 2 hard score levels is now infeasible
  if any of those hard levels is negative, even if one of them is positive (1 or higher).
  