In the schema editor, it's not possible to use "id" as a field name, but it's quite infortunate given my use case:
I want to create some sort of vocabulary, except it has some specific columns, so I have to create a custom schema for it. Except that if I want to be able to use the "vocabulary" widget type, I MUST have the id, ordering & obsolete fields in my schema, otherwise the widget will fail.
I could have managed to rename the "id" field to something else, unfortunately org.nuxeo.ecm.platform.ui.web.directory.SelectOneListboxComponent hardcodes the reference to "id", and the org.nuxeo.ecm.platform.ui.web.directory.DirectoryAwareComponent doesn't take the directory's "fieldId" option in consideration. Maybe an issue about that would be needed instead/too.
Another use case that would occur to me is if we want to use a directory to access a remote database having a table having an "id" column. It would require to rename the remote table, which is not always possible.
Unless there is some actual limitation in Studio itself, I don't see why we couldn't be able to use "id" since the property will eventually be "custom_schema:id", which doesn't conflict with anything I guess.