populate flake, flake-input: take the flake reference as url

Flake and flake-input sources take the flake reference as attribute url,
like git sources take their repository, and like inputs in flake.nix:

    something.flake = "github:owner/something";
    otherthing.flake = {
      url = "github:owner/otherthing";
      inputs.nixpkgs.follows = "nixpkgs";
    };

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/types/populate.nix b/lib/types/populate.nix
index 6193a19..4523dad 100644
--- a/lib/types/populate.nix
+++ b/lib/types/populate.nix
@@ -34,7 +34,7 @@
       flake = lib.mkOption {
         apply = x:
           if lib.types.str.check x
-            then { flake = x; }
+            then { url = x; }
             else x;
         default = null;
         type = lib.types.nullOr (lib.types.either lib.types.str source-types.flake);
@@ -178,7 +178,7 @@
           default = false;
           type = lib.types.bool;
         };
-        flake = lib.mkOption {
+        url = lib.mkOption {
           type = lib.types.str; # TODO lib.types.flake-ref
         };
         inputs = lib.mkOption {
@@ -193,7 +193,7 @@
           default = false;
           type = lib.types.bool;
         };
-        flake = lib.mkOption {
+        url = lib.mkOption {
           type = lib.types.str; # TODO lib.types.flake-ref
         };
         inputs = lib.mkOption {