@Test
public void ignoreEmptyFile() throws IOException {

    // we first need to remove the cached value
    InstanceUUID.uuid = null;
    Path path = Paths.get(OpenHAB.getUserDataFolder(), InstanceUUID.UUID_FILE_NAME);
    Files.createDirectories(path.getParent());
    Files.write(path, "".getBytes());
    String uuid = InstanceUUID.get();
    assertNotEquals("", uuid);
}