public Set<String> getDestinationFunctions() {
		if (vtSession == null) {
			throw new RuntimeException("You must have an open vt session");
		}
		return getFunctionNames(vtSession.getDestinationProgram());
	}
This will release the current session and both source and destination programs.
If either program needs to be held it is the script's responsibility to first retain
the instance and add itself as a consumer.  Any program consumer must release it
when done using it.
Ghidra/Features/VersionTracking/src/main/java/ghidra/feature/vt/AbstractGhidraVersionTrackingScript.java