The failure I looked at and managed to reproduce was apparently not the only possible failure. Right after pushing that, we got a new one finding this variation:

...\\windows-x64.jdk\\jdk-15\\bin\\jpackage.dll:
...\\open\\src\\jdk.incubator.jpackage\\share\\native\\common\\Toolbox.h

I will need to expand the exception I implemented in the test to match something like "jdk.incubator.jpackage.*h"