Java Template installs wrong JDK

[vbrandl]

The template for Java projects seems to install the wrong JDK.

I'm using the following flake.nix on NixOS/nixpkgs@a58bc8a:

{
  description = "A very basic flake";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
  };

  outputs = { self, nixpkgs }:
  let
    javaVersion = 22;
    supportedSystems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
    forEachSupportedSystem = f: nixpkgs.lib.genAttrs supportedSystems (system: f {
      pkgs = import nixpkgs { inherit system; };
    });
  in
  {
    overlays.default =
      final: prev: rec {
        jdk = prev."jdk${toString javaVersion}";
        maven = prev.maven.override { jre = jdk; };
      };

    devShells = forEachSupportedSystem ({ pkgs }: {
        default = pkgs.mkShell {
          packages = with pkgs; [ jdk maven ];
          MAVEN_OPTS = "--enable-preview";
        };
      });
  };
}

When I run nix shell .\#devShells.x86_64-linux.default (or activate the shell using direnv with use flake) and run java --version, I get openjdk 21.0.3 2024-04-16 instead of the expected Java 22.

My guess is, this is using the jdk package from nixpkgs, which is Java 21, instead of the jdk package from the overlay, which should be Java 22.

I'm not quite sure how to tell my flake to use the overlay...

Edit: Merging #53, #54 applying my comment from #54 seems to fix the issue for me.

[hatch01]

I am having the same issue, would love to see those PR merged