Score corruption in RockTour example

Caused by: java.lang.IllegalStateException: VariableListener corruption: the entity (Augusta, Maine)'s shadow variable (RockShow.date)'s corrupted value (2018-03-20) changed to uncorrupted value (2018-03-22) after all VariableListeners were triggered without changes to the genuine variables.
Maybe the VariableListener class (RockShowVariableListener) for that shadow variable (RockShow.date) forgot to update it when one of its sources changed after completedAction (Undo([Columbia, South Carolina..Madison, Wisconsin] {Pierre, South Dakota -reversing-> Austin, Texas})).
        at org.optaplanner.core.impl.score.director.AbstractScoreDirector.assertShadowVariablesAreNotStale(AbstractScoreDirector.java:552)
        at org.optaplanner.core.impl.score.director.AbstractScoreDirector.assertExpectedUndoMoveScore(AbstractScoreDirector.java:604)