Document why (if still appropriate) the following is specced
Created by: eileenmcnaughton
"IPN payment processors processing a contribution do NOT create civicrm_financial_item, civicrm_financial_trxn, or civicrm_entity_financial_trxn records at the time the transaction is posted to the payment processor. They are only created at the time of the IPN call back."
It's unclear from the document why we would not do the same things for Payment Processor & non payment processor payments. Historically the code treated the 2 very differently but in the real world the distinction has become very grey. If there is a good reason we should document it. Otherwise I suspect we have already started to 'leak' in the direction of treating them the same.