Preserve caller-supplied output streams

maven-executor/src/main/java/org/apache/maven/executor/ExecutorRequest.java

@@ -114,7 +114,7 @@ public interface ExecutorRequest {
      * Optional consumer for STD out of the Maven. If given, this consumer will get all output from the std out of
      * Maven. Note: whether consumer gets to consume anything depends on invocation arguments passed in
      * {@link #arguments()}, as if log file is set, not much will go to stdout.
-     * The stream is closed once tool execution is finished.
+     * The stream is not closed by the executor.
      *
      * @return an Optional containing the stdout consumer, or empty if not specified.
      */
@@ -124,7 +124,7 @@ public interface ExecutorRequest {
      * Optional consumer for STD err of the Maven. If given, this consumer will get all output from the std err of
      * Maven. Note: whether consumer gets to consume anything depends on invocation arguments passed in
      * {@link #arguments()}, as if log file is set, not much will go to stderr.
-     *  The stream is closed once tool execution is finished.
+     *  The stream is not closed by the executor.
      *
      * @return an Optional containing the stderr consumer, or empty if not specified.
      */

maven-executor/src/main/java/org/apache/maven/executor/support/ProcessBuilderExecutorSupport.java

@@ -121,9 +121,9 @@ protected CountDownLatch pump(Process p, InputStream stdIn, OutputStream stdOut,
         CountDownLatch latch = new CountDownLatch(3);
         String suffix = "-pump-" + ThreadLocalRandom.current().nextInt();
         Thread stdoutPump = new Thread(() -> {
-            try (OutputStream stdout = stdOut) {
-                IOTools.transferTo(p.getInputStream(), stdout);
-                stdout.flush();
+            try {
+                IOTools.transferTo(p.getInputStream(), stdOut);
+                stdOut.flush();
             } catch (IOException e) {
                 throw new UncheckedIOException(e);
             } finally {
@@ -134,9 +134,9 @@ protected CountDownLatch pump(Process p, InputStream stdIn, OutputStream stdOut,
         stdoutPump.setDaemon(true);
         stdoutPump.start();
         Thread stderrPump = new Thread(() -> {
-            try (OutputStream stderr = stdErr) {
-                IOTools.transferTo(p.getErrorStream(), stderr);
-                stderr.flush();
+            try {
+                IOTools.transferTo(p.getErrorStream(), stdErr);
+                stdErr.flush();
             } catch (IOException e) {
                 throw new UncheckedIOException(e);
             } finally {

maven-executor/src/test/java/org/apache/maven/executor/support/ProcessBuilderExecutorSupportTest.java

@@ -0,0 +1,81 @@
+/*
+ * 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.
+ */
+package org.apache.maven.executor.support;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+
+import org.apache.maven.executor.ExecutorRequest;
+import org.apache.maven.executor.ExecutorResult;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class ProcessBuilderExecutorSupportTest {
+
+    @Test
+    void doesNotCloseCallerOutputStreams() throws Exception {
+        Process process = new ProcessBuilder(System.getProperty("java.home") + "/bin/java", "-version").start();
+        TrackingOutputStream stdout = new TrackingOutputStream();
+        TrackingOutputStream stderr = new TrackingOutputStream();
+
+        new TestSupport()
+                .pump(
+                        process,
+                        new InputStream() {
+                            @Override
+                            public int read() {
+                                return -1;
+                            }
+                        },
+                        stdout,
+                        stderr)
+                .await();
+        process.waitFor();
+
+        assertFalse(stdout.closed);
+        assertFalse(stderr.closed);
+        assertTrue(stderr.toString(StandardCharsets.UTF_8.name()).contains("version"));
+    }
+
+    private static class TestSupport extends ProcessBuilderExecutorSupport {
+        @Override
+        public ExecutorResult execute(ExecutorRequest executorRequest) {
+            return null;
+        }
+
+        @Override
+        public String mavenVersion() {
+            return UNKNOWN_VERSION;
+        }
+    }
+
+    private static class TrackingOutputStream extends ByteArrayOutputStream {
+        private boolean closed;
+
+        @Override
+        public void close() throws IOException {
+            closed = true;
+            super.close();
+        }
+    }
+}