Backport #13363: restore the java.util.logging root handlers after an invocation

impl/maven-cli/src/main/java/org/apache/maven/cling/invoker/LookupInvoker.java

@@ -37,6 +37,7 @@
 import java.util.Properties;
 import java.util.function.Consumer;
 import java.util.function.UnaryOperator;
+import java.util.logging.Handler;
 
 import org.apache.maven.api.Constants;
 import org.apache.maven.api.ProtoSession;
@@ -124,6 +125,8 @@ public final int invoke(InvokerRequest invokerRequest) {
         Properties oldProps = new Properties();
         oldProps.putAll(System.getProperties());
         ClassLoader oldCL = Thread.currentThread().getContextClassLoader();
+        // activateLogging() replaces them with SLF4JBridgeHandler, whose classes live in Maven's realm
+        Handler[] oldRootLoggerHandlers = java.util.logging.Logger.getLogger("").getHandlers();
         try (C context = createContext(invokerRequest)) {
             if (contextConsumer != null) {
                 contextConsumer.accept(context);
@@ -147,6 +150,22 @@ public final int invoke(InvokerRequest invokerRequest) {
         } finally {
             Thread.currentThread().setContextClassLoader(oldCL);
             System.setProperties(oldProps);
+            restoreRootLoggerHandlers(oldRootLoggerHandlers);
+        }
+    }
+
+    /**
+     * Puts back the handlers the {@code java.util.logging} root logger had before the invocation. When Maven runs inside
+     * another JVM, the root logger belongs to that JVM, and a {@code SLF4JBridgeHandler} left on it would route the
+     * host's logging to Maven and fail once Maven's class realm is closed.
+     */
+    private static void restoreRootLoggerHandlers(Handler[] handlers) {
+        java.util.logging.Logger root = java.util.logging.Logger.getLogger("");
+        for (Handler handler : root.getHandlers()) {
+            root.removeHandler(handler);
+        }
+        for (Handler handler : handlers) {
+            root.addHandler(handler);
         }
     }
 

impl/maven-cli/src/test/java/org/apache/maven/cling/invoker/mvn/MavenInvokerTest.java

@@ -23,6 +23,8 @@
 import java.nio.file.Path;
 import java.util.List;
 import java.util.Map;
+import java.util.logging.ConsoleHandler;
+import java.util.logging.Handler;
 
 import com.google.common.jimfs.Configuration;
 import com.google.common.jimfs.Jimfs;
@@ -37,6 +39,7 @@
 import org.junit.jupiter.api.io.CleanupMode;
 import org.junit.jupiter.api.io.TempDir;
 
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertThrows;
@@ -66,6 +69,37 @@ void defaultFs(
         invoke(cwd, userHome, List.of("verify"), List.of());
     }
 
+    /**
+     * The invocation replaces the handlers of the {@code java.util.logging} root logger with {@code SLF4JBridgeHandler};
+     * they must be back afterwards, as the root logger belongs to the JVM Maven runs in (GH-13362).
+     */
+    @Test
+    void restoresJavaUtilLoggingRootHandlers(
+            @TempDir(cleanup = CleanupMode.ON_SUCCESS) Path cwd,
+            @TempDir(cleanup = CleanupMode.ON_SUCCESS) Path userHome)
+            throws Exception {
+        java.util.logging.Logger root = java.util.logging.Logger.getLogger("");
+        Handler[] original = root.getHandlers();
+        Handler marker = new ConsoleHandler();
+        for (Handler handler : original) {
+            root.removeHandler(handler);
+        }
+        root.addHandler(marker);
+        try {
+            invoke(cwd, userHome, List.of("validate"), List.of());
+
+            assertArrayEquals(new Handler[] {marker}, root.getHandlers());
+        } finally {
+            root.removeHandler(marker);
+            for (Handler handler : root.getHandlers()) {
+                root.removeHandler(handler);
+            }
+            for (Handler handler : original) {
+                root.addHandler(handler);
+            }
+        }
+    }
+
     @Disabled("Enable it when fully moved to NIO2 with Path/Filesystem (ie MavenExecutionRequest)")
     @Test
     void jimFs() throws Exception {