ENPresenter dumps the flavor code as text for null name parts.

[gschadow]

If I use this code to create a name:

list = new ArrayList();
list.add(vf.PNXPvalueOf("Hobo", EntityNamePartType.Given, null));
list.add(vf.PNXPvalueOf(null, EntityNamePartType.Given, null));
list.add(vf.PNXPvalueOf("Jobo", EntityNamePartType.Family, null));
list.add(vf.PNXPvalueOf(null, EntityNamePartType.Prefix, null));
list.add(vf.PNXPvalueOf(null, EntityNamePartType.Suffix, null));
pn = vf.PNvalueOf(list, null, null);

The output looks like this:

<name xsi:type="PN">
	<given>Hobo</given>NI<family>Jobo</family>NINI
</name>

Shouldn't it have things like: <prefix nullFlavor="NI"/> instead of just NI?

Yes it should. This must be a defect in the ENPresenter.