* instead of list, add an optional in method ServiceOrderAndServiceRepositories.addKubernetesResourceReferenceToEndUserReference ([05a2f97](https://labs.etsi.org/rep/osl/hypo/code/org.etsi.osl.hypo.api/tmf/commit/05a2f97d78632bdac8ccbd8fbb59fb9f9aabec97))