When Nuxeo makes some evolutions to the API that breaks the compatibility, my app still works as I can specify in the URL the version of the API I use (and the former version of the API is in the list of still supported versions).
Note: using the version segment is mandatory
Note bis : the version is used mostly for giving guarantees to the API user that the JSON entities won't change when migrating to newer version of Nuxeo.
Calling any of Nuxeo current REST Endpoint with the version segment equal to "v1" works
Callling any of Nuxeo current REST Endpoin without any version segment returns a webengine exception
Calling any of Nuxeo current REST Endpoint with any other string than "v1" returns webengine exception