As you've said, there's nothing in here that says how they're going to get this information, but by requiring that it be provided, it imposes an onus on the probation officer, I believe, to find it.
What tools does a probation officer have to know what the problems might be? If the accused is not interested or willing to come forward with information, I'm not sure how the probation officer will know about it. If he or she knows about it, what action can they take to get this information he is now required to give?