[xwiki-users] How to trigger an event or method on page delete?

I have implemented a xwiki based application in which there are two main classes "A" and "B". Those classes have a one-to-many relationship where one "A" can be associated with many "B"s. (Just like presented in https://www.xwiki.org/xwiki/bin/view/FAQ/HowToCreateAOneToManyRelationshipI… ) The main thing is that when I delete a page which contains and represents an "A" object, associated with many "B"s, those "B" pages still contain the reference to the no longer present "A" object. Therefore, I was hopping to find some kind of "onDelete" event triggered when a page is deleted so I could clean those dead references. Just to clarify: "B" objects have an attribute called "A-reference" where the doc.fullName of an "A" page is stored. If I could trigger a method when this "A" object is deleted I would be able to perform an HQL query in order to list those pages associated with the deleted "A" page and set a null value to the "A-reference" attribute. Would appreciate any thoughts and hints on how to solve this because I'm out of ideas and found no documentation on such event/trigger/method. Thanks! Francisco Barretto