Optapy | Can't compare LocalDateTime in join

Question

When i try to join on LocalDateTime in optapy i get a java.lang.NullPointerException

constraint_factory.for_each_unique_pair(Entity,
                            optapy.constraint.Joiners.greaterThan(lambda entity: entity.date, lambda entity: entity.date)) \
        .reward('Same date', optapy.score.SimpleScore.ONE),

java.lang.NullPointerException            Traceback (most recent call last)
File DefaultSolver.java:193, in org.optaplanner.core.impl.solver.DefaultSolver.solve()

java.lang.NullPointerException: java.lang.NullPointerException: Cannot invoke "java.util.List.iterator()" because "compareToMembers" is null

The above exception was the direct cause of the following exception:

java.lang.IllegalStateException           Traceback (most recent call last)
File DefaultSolver.java:193, in org.optaplanner.core.impl.solver.DefaultSolver.solve()

java.lang.IllegalStateException: java.lang.IllegalStateException: Joiner (GREATER_THAN) threw an exception matching left (2023-01-01T00:00) and right (2023-01-01T00:00) objects.

The above exception was the direct cause of the following exception:

Do i need to override implementation of method compareToMembers ?