Extend the vendor configuration

lib/modules/rclone.nix

@@ -78,7 +78,7 @@ let
     });
 
   mkWebdavProvider = (
-    { displayName, vendor, ... }: (
+    { displayName, vendor ? null, ... }: (
       { config, ... }: {
         imports = [
           mkProvider
@@ -86,7 +86,15 @@ let
 
         options = {
           vendor = lib.mkOption {
-            type = lib.types.str;
+            type = lib.types.nullOr (lib.types.enum [
+              "fastmail"
+              nextcloudVendor
+              owncloudVendor
+              "sharepoint"
+              "sharepoint-ntlm"
+              "rclone"
+              "other"
+            ]);
             description = "The vendor of the WebDAV share.";
             default = vendor;
           };
@@ -118,10 +126,8 @@ let
 
         config = {
           config = lib.mkMerge [
-            {
-              inherit vendor;
-              url = config.url;
-            }
+            { url = config.url; }
+            (mkIfNotNull config.vendor { inherit (config) vendor; })
             (mkIfNotNull config.username { user = config.username; })
             (mkIfNotNull config.obscuredPassword { pass = config.obscuredPassword; })
           ];