Enable Maven 4 build

.github/workflows/maven-verify.yml

@@ -50,3 +50,7 @@ jobs:
         !surefire-its/target/ConsoleOutputIT_*/target/surefire-reports/*-jvmRun*-events.bin
       timeout-minutes: 600
       os-matrix: '[ "ubuntu-latest", "windows-latest", "macos-latest" ]'
+      maven4-enabled: true
+      matrix-exclude: '[
+        { "jdk": "11", "maven": "4.0.0-rc-5" }
+      ]'

surefire-extensions-api/src/main/java/org/apache/maven/surefire/extensions/util/CountdownCloseable.java

@@ -53,7 +53,7 @@ public synchronized void close() throws IOException {
      * @throws InterruptedException see {@link Object#wait()}
      */
     public synchronized void awaitClosed() throws InterruptedException {
-        if (countdown > 0) {
+        while (countdown > 0) {
             wait();
         }
     }

surefire-its/src/test/java/org/apache/maven/surefire/its/fixture/MavenLauncher.java

@@ -76,8 +76,10 @@ public final class MavenLauncher {
         this.resourceName = resourceName;
         this.suffix = suffix != null ? suffix : "";
         this.cli = cli == null ? null : cli.clone();
-        // by default use embedded mode
-        this.forkJvm = false;
+        // Use forked mode for Maven 4+ because maven-verifier 2.0.0-M1's embedded mode
+        // uses reflection against MavenCling.doMain() with an incompatible method signature.
+        // Once surefire migrates from maven-verifier to maven-executor, this can be removed.
+        this.forkJvm = isMaven4();
         resetGoals();
         resetCliOptions();
     }
@@ -409,6 +411,32 @@ private static Verifier createVerifier(String basedir, String settingsFile, Stri
                 : new Verifier(basedir, settingsFile, false, defaultCliOptions);
     }
 
+    /**
+     * Detects if the current Maven installation is version 4.x or later by checking for the
+     * presence of {@code maven-cli-*.jar} in the Maven home lib directory. Maven 4 introduced
+     * the {@code maven-cli} module which is not present in Maven 3.x installations.
+     *
+     * @return {@code true} if Maven 4+ is detected
+     */
+    private static boolean isMaven4() {
+        String mavenHome = System.getProperty("maven.home", "");
+        if (mavenHome.isEmpty()) {
+            return false;
+        }
+        File libDir = new File(mavenHome, "lib");
+        if (libDir.isDirectory()) {
+            String[] files = libDir.list();
+            if (files != null) {
+                for (String file : files) {
+                    if (file.startsWith("maven-cli-")) {
+                        return true;
+                    }
+                }
+            }
+        }
+        return false;
+    }
+
     private static File settingsXmlPath() {
         try {
             return new File(System.getProperty("maven.settings.file")).getCanonicalFile();