There's no seam data in http://apidoc.nuxeo.com/nuxeo/ for 7.10, 8.1, 8.2, 8.3.
http://explorer.nuxeo.com/nuxeo/site/distribution/Nuxeo%20DM-7.10/listSeamComponents is KO (empty)
http://explorer.nuxeo.com/nuxeo/site/distribution/Nuxeo%20DM-8.3/listSeamComponents is KO (empty)
http://explorer.nuxeo.com/nuxeo/site/distribution/cap-8.3/listSeamComponents is OK (this is the live instance)
http://explorer.nuxeo.com/nuxeo/site/distribution/Nuxeo%20Platform%20LTS%202016-8.10/listSeamComponents is OK.
Even if the /listSeamComponents endpoint is no more exposed in the UI, it is still working and there are pointers from the documentation.
There are chances that the data is missing because the instructions at Release of Nuxeo Platform have not been properly followed
3. browse http://localhost:8080/nuxeo/site/distribution/current/listSeamComponents (to initialize Seam introspection),
=> reimport the data for 7.10, 8.1, 8.2, 8.3