I have a <many-to-one> relationship to a class with lazy=true. But they are not related by "ID" column, they are related by property-ref. And the loading get all the real object of the related class.

I think property-ref means the related object shall be unique identified, there shall not be problem to get the proxy first.

Proxies are implemented so that they only store the ID field, and query the database to load the whole object by that ID, when needed. And since the ID of a property-ref'ed object is not known, it can't be proxied.