public synchronized void invalidate() {
		hardCache.clear();
		processQueue();
		if (++invalidateCount <= 0) {
			invalidateCount = 1;
			for (KeyedSoftReference<T> ref : map.values()) {
				DatabaseObject obj = ref.get();
				if (obj != null) {
					obj.setInvalid();
				}
			}
		}
	}
Marks all the cached objects as invalid.  Invalid objects will have to refresh themselves
before they are allowed to be used. If an invalidated object cannot refresh itself, then
the object is removed from the cache and discarded and the application can no longer use
that instance of the object.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/DBObjectCache.java