Using nix flakes for developer shell (OpenAPITools#14888)

Author: msosnicki

.envrc

@@ -0,0 +1 @@
+use flake

.gitignore

@@ -35,6 +35,7 @@ packages/
 nbproject/
 nbactions.xml
 nb-configuration.xml
+.direnv/
 
 .settings
 

README.md

@@ -263,6 +263,20 @@ If you don't have maven installed, you may directly use the included [maven wrap
 ./mvnw clean install
 ```
 
+#### Nix users
+
+If you're a nix user, you can enter OpenAPI Generator shell, by typing:
+```sh
+nix develop
+```
+It will enter a shell with Java 8 and Maven installed. 
+
+Direnv supports automatically loading of the nix developer shell, so if you're using direnv too, type:
+```sh
+direnv allow
+```
+and have `java` and `mvn` set up with correct versions each time you enter project directory.
+
 The default build contains minimal static analysis (via CheckStyle). To run your build with PMD and Spotbugs, use the `static-analysis` profile:
 
 ```sh

flake.lock

@@ -0,0 +1,23 @@
+{
+  description = "OpenAPI generator nix flake";
+
+  inputs.nixpkgs.url = "github:nixos/nixpkgs";  
+  inputs.flake-utils.url = "github:numtide/flake-utils";
+
+  outputs = { self, nixpkgs, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs { inherit system; };
+      in
+      {
+        devShells.default = pkgs.mkShell
+          {
+            buildInputs = with pkgs;[
+              jdk8
+              maven
+            ];
+          };
+      }
+    );
+}
+