There is no way today to check quickly in the sources if an icon is deprecated or not.
It is touchy to remove an icon from the platform: even if we don't use it in the main bundles, we never know if the icon is not used in a marketplace or custom bundle.
- add a deprecated folder in the icon managers packages (nuxeo-jsf/nuxeo-platform-webapp-base and nuxeo-dm/nuxeo-platform-webapp for now).
- in each deprecated folder, add 2 folders: one for the latest release version, one for the following, see the following example:
For the next 5.7 release, the 5.6 folder will be deleted and a 5.8 folder will be created. That way, we keep the deprecated icons during a version, and we can list all the icons in the upgrade note.
Another solution would be to have a backward compatibility bundle for each release, to add only when you notice that some icons are missing in your project.