public synchronized void cacheMaint() {
		//Msg.info(this, "Performing filesystem cache maint");
		List<FSCacheInfo> recsToPurge = getExpired(getUnusedFSes());
		if (!recsToPurge.isEmpty()) {
			Msg.info(this, "Evicting " + recsToPurge.size() + " filesystems from cache");
		}
		for (FSCacheInfo fsci : recsToPurge) {
			release(fsci);
		}
	}
Performs maintainence on the filesystem cache, closing() any filesystems
that are not used anymore.
Ghidra/Features/Base/src/main/java/ghidra/formats/gfilesystem/FileSystemInstanceManager.java