Override "jta-data-source" with system properties?

[KARR, DAVID (ATTCINW)]

My main "persistence.xml" file specifies a "jta-data-source" element, as
that's what the real app is going to use.  I'm going to attempt to build
Derby-based test cases for this whichi use the existing persistence.xml,
but overrides the database settings.  If I have the "jta-data-source"
element set in the persistence.xml, but I set the "openjpa.*" system
properties to point to my in-memory Derby database, will the
"jta-data-source" setting create any problem for me?