Mill Module (#22652)

* Initial Mill support

* Updated Docs after changing git and pom settings to case classes

* Update Docs

* include Mill plugin in Docker build

* fix scaladoc

* fix cubic-dev-ai findings

Author: lostiniceland

Dockerfile

@@ -13,6 +13,7 @@ COPY ./google_checkstyle.xml ${GEN_DIR}
 # All poms are copied, then we go offline, to allow for better caching of code changes without fetching all dependencies each time
 COPY ./modules/openapi-generator-gradle-plugin/pom.xml ${GEN_DIR}/modules/openapi-generator-gradle-plugin/
 COPY ./modules/openapi-generator-maven-plugin/pom.xml ${GEN_DIR}/modules/openapi-generator-maven-plugin/
+COPY ./modules/openapi-generator-mill-plugin/pom.xml ${GEN_DIR}/modules/openapi-generator-mill-plugin/
 COPY ./modules/openapi-generator-online/pom.xml ${GEN_DIR}/modules/openapi-generator-online/
 COPY ./modules/openapi-generator-cli/pom.xml ${GEN_DIR}/modules/openapi-generator-cli/
 COPY ./modules/openapi-generator-core/pom.xml ${GEN_DIR}/modules/openapi-generator-core/
@@ -23,6 +24,7 @@ RUN mvn dependency:go-offline
 # Modules are copied individually here to allow for caching of docker layers between major.minor versions
 COPY ./modules/openapi-generator-gradle-plugin ${GEN_DIR}/modules/openapi-generator-gradle-plugin
 COPY ./modules/openapi-generator-maven-plugin ${GEN_DIR}/modules/openapi-generator-maven-plugin
+COPY ./modules/openapi-generator-mill-plugin ${GEN_DIR}/modules/openapi-generator-mill-plugin
 COPY ./modules/openapi-generator-online ${GEN_DIR}/modules/openapi-generator-online
 COPY ./modules/openapi-generator-cli ${GEN_DIR}/modules/openapi-generator-cli
 COPY ./modules/openapi-generator-core ${GEN_DIR}/modules/openapi-generator-core

docs/plugins.md

@@ -120,3 +120,56 @@ openApiGenerate {
 ```
 
 *If you want to create separate tasks (for example when you have more than one api spec and require different parameters for each), this is how to do so in Gradle 7+: `tasks.register('taskName', org.openapitools.generator.gradle.plugin.tasks.GenerateTask) { ... }`.*
+
+## Mill
+
+This Mill library provides a Mill module that can be used to generate code from OpenAPI specifications.
+
+### Example
+
+```scala
+//| mill-version: 1.0.6
+//| mvnDeps:
+//|   - org.openapitools:openapi-generator-mill-plugin:7.19.0 # 1.
+
+import mill.*
+
+import org.openapitools.generator.mill.OpenApiModule // 2.
+
+object `package` extends JavaModule with MavenModule with OpenApiModule { // 3.
+
+  // other Mill config...
+  
+  object openapi extends OpenApiConfig { // 4.
+    def inputSpec: T[PathRef] = Task.Source(BuildCtx.workspaceRoot / "api" / "petstore.yaml")
+    // other config options...
+  }
+
+  override def generatedSources: T[Seq[PathRef]] = Seq(
+    PathRef(Task.dest),
+    openapi.generate(), // 5.
+  )
+}
+```
+
+1. Add the plugin to your `build.mill` as `mvnDeps` in the header section
+2. import `org.openapitools.generator.mill.OpenApiModule`
+3. add `OpenApiModule` to the module definition
+4. configure 1-n `OpenApiConfig` as sub-modules
+5. run the generation as part of the `compile` task
+
+This gives access to the following tasks:
+
+| Task                      | Description                                                                                 |
+|---------------------------|---------------------------------------------------------------------------------------------|
+| <configName>.generate     | Generate code via Open API Tools Generator for Open API 2.0 or 3.x specification documents. |
+| <configName>.validateSpec | Validates the configured spec                                                               |
+
+and a command
+
+| Command             | Description                                    |
+|---------------------|------------------------------------------------|
+| validateOpenapiSpec | Takes the path to a spec file and validates it |
+
+
+For full details of all options, see the [plugin README](https://github.com/OpenAPITools/openapi-generator/tree/master/modules/openapi-generator-mill-plugin).

modules/openapi-generator-mill-plugin/README.md

@@ -0,0 +1,9 @@
+To test the Mill plugin, this project can be used.
+
+> ![NOTE]
+> The `mill-build` folder is only needed to look up the plugin from the local Maven repository for development purposes.
+
+It requires that the current SNAPSHOT version of the plugin is installed in the local Maven repository.
+Replace the version in `build.mill` or set the environment variable `$MILL_OPENAPITOOLS_PLUGIN_VERSION` to the desired version.
+
+Run `./mill __.compile` to test if the plugin works or some of the modules tasks like `./mill openapi.validate`.

modules/openapi-generator-mill-plugin/mill-test/README.md

@@ -0,0 +1,103 @@
+openapi: "3.0.0"
+servers:
+  - url: http://petstore.swagger.io/v1
+paths:
+  /pets:
+    get:
+      summary: List all pets
+      operationId: listPets
+      tags:
+        - pets
+      parameters:
+        - name: limit
+          in: query
+          description: How many items to return at one time (max 100)
+          required: false
+          schema:
+            type: integer
+            format: int32
+      responses:
+        '200':
+          description: A paged array of pets
+          headers:
+            x-next:
+              description: A link to the next page of responses
+              schema:
+                type: string
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Pets"
+        default:
+          description: unexpected error
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Error"
+    post:
+      summary: Create a pet
+      tags:
+        - pets
+      responses:
+        '201':
+          description: Null response
+        default:
+          description: unexpected error
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Error"
+  /pets/{petId}:
+    get:
+      summary: Info for a specific pet
+      operationId: showPetById
+      tags:
+        - pets
+      parameters:
+        - name: petId
+          in: path
+          required: true
+          description: The id of the pet to retrieve
+          schema:
+            type: string
+      responses:
+        '200':
+          description: Expected response to a valid request
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Pets"
+        default:
+          description: unexpected error
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Error"
+components:
+  schemas:
+    Pet:
+      required:
+        - id
+        - name
+      properties:
+        id:
+          type: integer
+          format: int64
+        name:
+          type: string
+        tag:
+          type: string
+    Pets:
+      type: array
+      items:
+        $ref: "#/components/schemas/Pet"
+    Error:
+      required:
+        - code
+        - message
+      properties:
+        code:
+          type: integer
+          format: int32
+        message:
+          type: string