Generates automatically a marker file for a maven profile depending o…

…n java level to use

The current logic of setting `maven.compiler.release` dynamically works fine for the Maven CLI. However IDE support (at least IntelliJ) doesn't work well with this and happily ignores what the plugin set dynamically.

Instead, it picks up the default value set through the plugin pom that defaults to the minimum java version supported (currently [11](https://github.com/jenkinsci/plugin-pom/blob/6949f8af159d30e2722fcf773b397bc870e47359/pom.xml#L61)), instead of the version inferred from Java bytecode version obtained from Jenkins core.

Generating markerfiles allow to enable maven profiles that will set the java release to the correct version when loaded in IDE.

src/it/ensure-java-level-marker-11-migration/invoker.properties

@@ -0,0 +1,20 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+invoker.goals=-ntp validate

src/it/ensure-java-level-marker-11-migration/pom.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>org.jenkins-ci.plugins</groupId>
+    <artifactId>plugin</artifactId>
+    <version>4.77</version>
+    <relativePath />
+  </parent>
+  <groupId>org.jenkins-ci.tools.hpi.its</groupId>
+  <artifactId>ensure-java-level-marker-11-migration</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <packaging>hpi</packaging>
+  <name>MyNewPlugin</name>
+  <properties>
+    <jenkins.version>2.361.4</jenkins.version>
+    <hpi-plugin.version>@project.version@</hpi-plugin.version>
+    <spotless.check.skip>false</spotless.check.skip>
+  </properties>
+</project>

src/it/ensure-java-level-marker-11-migration/verify.groovy

@@ -0,0 +1,24 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+assert new File(basedir, 'target/java-level').list().length == 1
+assert new File(basedir, 'target/java-level/11').exists()
+assert new File(basedir, 'build.log').getText('UTF-8').contains("Removing old marker file")
+
+return true

src/it/ensure-java-level-marker-11/invoker.properties

@@ -0,0 +1,20 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+invoker.goals=-ntp validate

src/it/ensure-java-level-marker-11/pom.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>org.jenkins-ci.plugins</groupId>
+    <artifactId>plugin</artifactId>
+    <version>4.77</version>
+    <relativePath />
+  </parent>
+  <groupId>org.jenkins-ci.tools.hpi.its</groupId>
+  <artifactId>ensure-java-level-marker-11</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <packaging>hpi</packaging>
+  <name>MyNewPlugin</name>
+  <properties>
+    <jenkins.version>2.361.4</jenkins.version>
+    <hpi-plugin.version>@project.version@</hpi-plugin.version>
+    <spotless.check.skip>false</spotless.check.skip>
+  </properties>
+</project>

src/it/ensure-java-level-marker-11/verify.groovy

@@ -0,0 +1,23 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+assert new File(basedir, 'target/java-level').list().length == 1
+assert new File(basedir, 'target/java-level/11').exists()
+
+return true

src/main/java/org/jenkinsci/maven/plugins/hpi/ValidateMojo.java

@@ -2,12 +2,16 @@
 
 import hudson.util.VersionNumber;
 import io.jenkins.lib.versionnumber.JavaSpecificationVersion;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.Properties;
 import org.apache.maven.model.Scm;
 import org.apache.maven.plugin.MojoExecutionException;
 import org.apache.maven.plugins.annotations.LifecyclePhase;
 import org.apache.maven.plugins.annotations.Mojo;
 import org.apache.maven.project.MavenProject;
+import org.codehaus.plexus.util.FileUtils;
 
 /**
  * Make sure that we are running in the right environment.
@@ -37,6 +41,7 @@ public void execute() throws MojoExecutionException {
         if (JavaSpecificationVersion.forCurrentJVM().isOlderThan(javaVersion)) {
             throw new MojoExecutionException("Java " + javaVersion + " or later is necessary to build this plugin.");
         }
+        writeProfileMarker(javaVersion);
 
         if (new VersionNumber(findJenkinsVersion()).compareTo(new VersionNumber("2.361")) < 0) {
             throw new MojoExecutionException("This version of maven-hpi-plugin requires Jenkins 2.361 or later");
@@ -94,6 +99,56 @@ public void execute() throws MojoExecutionException {
         }
     }
 
+    private void writeProfileMarker(JavaSpecificationVersion javaVersion) throws MojoExecutionException {
+        var path = Path.of(project.getBuild().getDirectory(), "java-level");
+        if (!Files.exists(path)) {
+            try {
+                Files.createDirectories(path);
+            } catch (IOException e) {
+                throw new MojoExecutionException("Failed to create " + path, e);
+            }
+        }
+        var versionPath = path.resolve(Integer.toString(javaVersion.toReleaseVersion()));
+        boolean found = false;
+        try (var walk = Files.walk(path)) {
+            for (var it = walk.iterator(); it.hasNext(); ) {
+                var p = it.next();
+                if (p.equals(path)) {
+                    continue;
+                }
+                if (!p.equals(versionPath)) {
+                    getLog().info("Removing old marker file " + p);
+                    delete(p);
+                } else {
+                    found = true;
+                }
+            }
+        } catch (IOException e) {
+            throw new MojoExecutionException("Failed to walk " + path, e);
+        }
+        if (!found) {
+            try {
+                Files.createFile(versionPath);
+                getLog().info("Created marker file " + versionPath);
+            } catch (IOException e) {
+                throw new MojoExecutionException("Failed to create file " + versionPath, e);
+            }
+        }
+    }
+
+    private static void delete(Path p) throws MojoExecutionException {
+        try {
+            if (Files.isRegularFile(p)) {
+                Files.delete(p);
+            } else if (Files.isDirectory(p)) {
+                // In case someone manually created a subdirectory, delete it recursively
+                FileUtils.deleteDirectory(p.toFile());
+            }
+        } catch (IOException e) {
+            throw new MojoExecutionException("Failed to delete " + p, e);
+        }
+    }
+
     private void check(String tag, String value, String badStart, String goodStart, String reason) {
         if (value.startsWith(badStart)) {
             String goodValue = goodStart + value.substring(badStart.length());