Contributions without an "id" or "name" attribute (or with empty values for these attributes) will not behave correctly on the "override" mechanism (as it hardcodes the id retrieval with these attributes)
Steps to reproduce: on 11.1, navigate to http://localhost:8080/nuxeo/site/distribution/server-11.1-SNAPSHOT/viewContribution/cluster-config--configuration and generate an override.
The contribution original source:
<extension point="configuration" target="org.nuxeo.runtime.cluster.ClusterService"> <clusterNode enabled="" id=""/> </extension>