Some preparations for supporting principal memberships

crates/carddav/src/addressbook/methods/mkcol.rs

@@ -48,7 +48,7 @@ pub async fn route_mkcol<AS: AddressbookStore>(
     root_span: RootSpan,
 ) -> Result<HttpResponse, Error> {
     let (principal, addressbook_id) = path.into_inner();
-    if principal != user.id {
+    if !user.is_principal(&principal) {
         return Err(Error::Unauthorized);
     }