How to set XMLIGNORENULL for non %String property?

By extending %XML.Adaptor, we can use

Parameter XMLIGNORENULL   

to handle empty tags in output xml file from %Persistent. But this parameter only applies to %String property. What if a class has other types of properties, like %Stream (for holding large chunk of data). What is the recommended handle if we cannot use XMLIGNORENULL here?

Context: In change control, exported .xml file is important to make diff between versions. To correctly handle edits on a previously null property (for example, the first edit to store value in "Data" field), we need XMLIGNORENULL to be "inputonly" so that our stream data can be check out and revert in change control management.