public synchronized boolean canClose(FileSystemRef callersRef) {
		return refs.size() == 1 && refs.get(0) == callersRef;
	}
Returns true if the only {@link FileSystemRef} pinning this filesystem is the
caller's ref.

@param callersRef {@link FileSystemRef} to test
@return boolean true if the tested {@link FileSystemRef} is the only ref pinning
the filesystem.
Ghidra/Features/Base/src/main/java/ghidra/formats/gfilesystem/FileSystemRefManager.java