To reproduce, adjust VehicleRoutingConstraintProviderTest to adjust a unit test that a zero score and assert that it has a different score (for example 3000L).

The error message looks like this:

java.lang.AssertionError: Broken expectation.
        Constraint: org.optaplanner.examples.vehiclerouting.domain/arrivalAfterDueTime
  Expected penalty: 3000 (class java.lang.Long)
    Actual penalty: 0 (class java.lang.Integer)

At this point, the "(class java.lang.Integer)" is a "red herring". It's very confusing.

Proposal A)
Remove "(class ...)" if the score is zero

Proposal B)
Fix it properly if possible Have it deduct that it's should say 0 (class java.lang.Long) there.

In fact, if we use a penalisesBy(int) for a BigDecimalSoftScore, I 'd love to see a second line in the error message that says "Maybe call the correct penalizesBy() overloaded method."
Look for usages of the word "Maybe" in optaplanner-core error messages. The idea is the first line shows the problem and the second line suggest a solution that might or might not work (hence the word "maybe").