formats.javaProperties: Add comment

pkgs/pkgs-lib/formats/java-properties/default.nix

@@ -1,6 +1,6 @@
 { lib, pkgs }:
 {
-  javaProperties = {}: {
+  javaProperties = { comment ? "Generated with Nix" }: {
     type = lib.types.attrsOf lib.types.str;
 
     generate = name: value:
@@ -76,10 +76,15 @@
 
           inputEncoding = "UTF-8";
 
+          inherit comment;
+
         } ''
+        (
+          echo "$comment" | while read -r ln; do echo "# $ln"; done
+          echo
           jq -r --arg hash '#' "$jqCode" "$valuePath" \
             | iconv --from-code "$inputEncoding" --to-code JAVA \
-          > "$out"
+        ) > "$out"
       '';
   };
 }

pkgs/pkgs-lib/tests/formats.nix

@@ -179,6 +179,8 @@ in runBuildTests {
       "الجبر" = "أكثر من مجرد أرقام";
     };
     expected = ''
+      # Generated with Nix
+
       1 = 2
       foo = bar
       \u00fctf\ 8 = d\u00fbh