Integrated example project for Mill into CI task (#22702)

* Integrated example project for Mill into CI task

The example project uses Mills meta-build to resolve the snapshot version from a properties file.
The properties-file is now integrated into `release_version_update.sh`.

* Add coursier cache to actions-cache

* Split Mill tests into separate steps

* try to exclude problematic dependencies from maven-cache so they are downloaded by coursier

* clear m2-cache prior to mill execution

Author: lostiniceland

.github/workflows/mill-plugin-tests.yaml

@@ -0,0 +1,69 @@
+name: Mill plugin tests
+
+on:
+  push:
+    paths:
+      - modules/openapi-generator-mill-plugin/**
+  pull_request:
+    paths:
+      - modules/openapi-generator-mill-plugin/**
+
+jobs:
+  test:
+    name: Mill plugin tests
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - name: Set up JDK 11
+        uses: actions/setup-java@v5
+        with:
+          java-version: 11
+          distribution: 'temurin'
+      - name: Restore cache (read-only)
+        # only use restore keys, no save key because we need to clear the cache before running the examples
+        uses: actions/cache/restore@v4
+        with:
+          path: |
+            ~/.m2/repository
+            ~/.gradle
+            ~/.cache/coursier
+            !~/.gradle/caches/*/plugin-resolution/
+            !~/.m2/repository/org/openapitools/
+            !~/.cache/coursier/v1/https/repo1.maven.org/maven2/org/openapitools/
+          key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/pom.xml') }}
+
+      - name: Maven Clean Install
+        env:
+          GRADLE_ENTERPRISE_ACCESS_KEY: ${{ secrets.GRADLE_ENTERPRISE_ACCESS_KEY }}
+        run: |
+          ./mvnw clean install -DskipTests -Dmaven.javadoc.skip=true
+
+      # This is needed because of differences in how Maven and Coursier download artifacts
+      # Maven will only download the pom when the transitive dependency is not needed in the current projects compile classpath
+      # whereas Coursier expects the artifact (jar) to be present in a Maven repository. When Coursier encounters a
+      # artifact folder with a pom it considers the artifact to be available and will then crash when the jar is missing.
+      - name: Clear m2 cache except openapitools (because otherwise coursier will fail to resolve artifacts where only poms are downloaded)
+        run: |
+          mv ~/.m2/repository/org/openapitools /tmp/openapitools-backup || true
+          rm -rf ~/.m2/repository/*
+          mkdir -p ~/.m2/repository/org
+          mv /tmp/openapitools-backup ~/.m2/repository/org/openapitools || true
+
+      - name: Mill Example - Test Validation Command
+        env:
+          GRADLE_ENTERPRISE_ACCESS_KEY: ${{ secrets.GRADLE_ENTERPRISE_ACCESS_KEY }}
+        run: |
+          (cd modules/openapi-generator-mill-plugin/example/ && ./mill validateOpenapiSpec $(pwd)/api/petstore-invalid.yaml)
+
+      - name: Mill Example - Test Validation Task
+        env:
+          GRADLE_ENTERPRISE_ACCESS_KEY: ${{ secrets.GRADLE_ENTERPRISE_ACCESS_KEY }}
+        run: |
+          (cd modules/openapi-generator-mill-plugin/example/ && ./mill openapi.validate)
+
+      - name: Mill Example - Test Compile Task
+        env:
+          GRADLE_ENTERPRISE_ACCESS_KEY: ${{ secrets.GRADLE_ENTERPRISE_ACCESS_KEY }}
+        run: |
+          (cd modules/openapi-generator-mill-plugin/example/ && ./mill __.compile)
+          

bin/utils/release/release_version_update.sh

@@ -93,6 +93,7 @@ declare -a xml_files=(
 declare -a properties_files=(
     "${root}/modules/openapi-generator-gradle-plugin/gradle.properties"
     "${root}/modules/openapi-generator-gradle-plugin/samples/local-spec/gradle.properties"
+    "${root}/modules/openapi-generator-mill-plugin/example/mill-build/version.properties"
 )
 
 ${cwd}/bump.sh -f ${version} -i ${inc} ${xml_files[@]}

…mill-test/api/petstore-v3.0-invalid.yaml …plugin/example/api/petstore-invalid.yamlmodules/openapi-generator-mill-plugin/mill-test/api/petstore-v3.0-invalid.yaml renamed to modules/openapi-generator-mill-plugin/example/api/petstore-invalid.yaml modules/openapi-generator-mill-plugin/mill-test/api/petstore-v3.0-invalid.yaml renamed to modules/openapi-generator-mill-plugin/example/api/petstore-invalid.yaml

@@ -1,7 +1,8 @@
 //| mill-version: 1.0.6
-//| mvnDeps:
-//|   - com.lihaoyi::mill-contrib-versionfile:$MILL_VERSION
-//|   - org.openapitools:openapi-generator-mill-plugin:$MILL_OPENAPITOOLS_PLUGIN_VERSION
+//| # usually you would add the plugin dependency like the following,
+//| # but for testing with SNAPSHOT versions, the plugin dependency is added in the meta-build
+//| # mvnDeps:
+//| #  - org.openapitools:openapi-generator-mill-plugin:$MILL_OPENAPITOOLS_PLUGIN_VERSION
 //|
 package build
 
@@ -12,15 +13,12 @@ import mill.scalalib.publish.PomSettings
 import mill.util.BuildInfo.{millBinPlatform, millVersion}
 import javalib.*
 
-import mill.contrib.versionfile.VersionFileModule
 import org.openapitools.generator.mill.OpenApiModule
 
 object `package` extends JavaModule with MavenModule with OpenApiModule {
 
-  // dependency on openapi-generator is set in Mills meta-build
-  // this is needed to point to a local maven repo
   override def mvnDeps = Seq(
-    mvn"jakarta.platform:jakarta.jakartaee-api:11.0.0",
+    mvn"jakarta.platform:jakarta.jakartaee-api:10.0.0",
     mvn"com.fasterxml.jackson.core:jackson-databind:2.20.0",
     mvn"org.openapitools:jackson-databind-nullable:0.2.8"
   )

…-mill-plugin/mill-test/api/petstore.yaml …or-mill-plugin/example/api/petstore.yamlmodules/openapi-generator-mill-plugin/mill-test/api/petstore.yaml renamed to modules/openapi-generator-mill-plugin/example/api/petstore.yaml modules/openapi-generator-mill-plugin/mill-test/api/petstore.yaml renamed to modules/openapi-generator-mill-plugin/example/api/petstore.yaml

@@ -0,0 +1,36 @@
+
+import coursier.LocalRepositories.Dangerous
+import coursier.Repositories
+import mill.scalalib.DepSyntax
+import mill.*
+import mill.api.Task
+import mill.meta.MillBuildRootModule
+import java.util.Properties
+import java.io.FileInputStream
+import scala.util.Using
+
+object `package` extends MillBuildRootModule {
+
+  override def repositories = Task {
+    Seq(
+      // central needed for default deps
+      Repositories.central.root,
+      // the previously installed snapshot is in local maven
+      // see docs on Coursier, why m2 is considered dangerous
+      Dangerous.maven2Local.root)
+  }
+
+  def propsFile = Task.Source("version.properties")
+
+  def readOpenapiSnapshotVersion: Task[String] = Task {
+    val props = new Properties()
+    Using(new FileInputStream(propsFile().path.toIO)) { fis =>
+      props.load(fis)
+      props.getProperty("openApiGeneratorVersion")
+    }.get
+  }
+
+  override def mvnDeps = Seq(
+    mvn"org.openapitools:openapi-generator-mill-plugin:${readOpenapiSnapshotVersion()}"
+  )
+}

…nerator-mill-plugin/mill-test/build.mill …generator-mill-plugin/example/build.millmodules/openapi-generator-mill-plugin/mill-test/build.mill renamed to modules/openapi-generator-mill-plugin/example/build.mill modules/openapi-generator-mill-plugin/mill-test/build.mill renamed to modules/openapi-generator-mill-plugin/example/build.mill

@@ -0,0 +1,3 @@
+# RELEASE_VERSION
+openApiGeneratorVersion=7.19.0-SNAPSHOT
+# /RELEASE_VERSION