Need Negative Test that gets unparser namespace ambiguity error

When using JSON, because there are no namespaces there are ambiguous situations where the unparser gets an element name, but it doesn't know what element to synthesize in the infoset because it has more than one possibility that differ only by namespace.

No test elicits this message.

The message string (you can search for) is:

"Found multiple matches for element %s because infoset implementation ignores namespaces"