Are instances of Class?> immutable?

I was wondering whether Class<?> instances are immutable. The declared methods names do not suggest that the instance state is changed when they are invoked, but I found no explicit guarantee on the javadoc.

Scenario: I need to store unique class names in a Set. Ideally, I would like to populate the set with Class<?> instances to avoid unnecessary calls to Class.forName() when I need to access the classe via reflection. However, it preferable to use immutable objects as keys of sets. Hence I was wondering if I could use Class<?> instances right away.