if this class can be loaded, the JPF core is in the CLASSPATH.
The reason to use an empty, non-instantiable tag class for this is to make
sure we don't get conflicts between CLs - this class should not be used
for anything but to check if it can be found
NOTE - this class has to be reachable through the same CP entry like
gov.nasa.jpf.JPF and gov.nasa.jpf.Config