from(Lesson::class.java)
                .filter { it.timeslot != null }
                .groupBy({ it.studentGroup }, { it.timeslot!!.day }, ConstraintCollectors.toList())
                .filter { group, day, list ->
                    list.any { it.timeslot!!.number != 1 }
                }
                .penalize(
                    "Student must have first lesson",
                    HardSoftScore.ONE_HARD
                ) { group, day, list -> list.count { it.timeslot!!.number != 1 } },

Undo for (Lesson(subj...)) does not exist