Add IT and fix a bug

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

@@ -181,7 +181,9 @@ protected Optional<Map<String, String>> collectMapIfPresentOrEmpty(
             Optional<Map<String, String>> up = getter.apply(option);
             if (up.isPresent()) {
                 had++;
-                items.putAll(up.get());
+                for (Map.Entry<String, String> entry : up.get().entrySet()) {
+                    items.putIfAbsent(entry.getKey(), entry.getValue());
+                }
             }
         }
         return had == 0 ? Optional.empty() : Optional.of(Map.copyOf(items));

its/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng8594AtFileTest.java

@@ -0,0 +1,64 @@
+/*
+ * 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.it;
+
+import java.nio.file.Path;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.Assert.assertTrue;
+
+/**
+ * This is a test set for <a href="https://issues.apache.org/jira/browse/MNG-8594">MNG-8594</a>.
+ */
+class MavenITmng8594AtFileTest extends AbstractMavenIntegrationTestCase {
+
+    MavenITmng8594AtFileTest() {
+        super("[4.0.0-rc-3-SNAPSHOT,)");
+    }
+
+    /**
+     *  Verify Maven picks up params/goals from atFile.
+     */
+    @Test
+    void testIt() throws Exception {
+        Path basedir = extractResources("/mng-8594").getAbsoluteFile().toPath();
+
+        Verifier verifier = newVerifier(basedir.toString());
+        verifier.addCliArgument("-af");
+        verifier.addCliArgument("cmd.txt");
+        verifier.addCliArgument("-Dcolor1=green");
+        verifier.addCliArgument("-Dcolor2=blue");
+        verifier.addCliArgument("clean");
+        verifier.execute();
+        verifier.verifyErrorFreeLog();
+
+        // clean did run
+        verifier.verifyTextInLog("(default-clean) @ root");
+        // validate bound plugin did run
+        verifier.verifyTextInLog("(eval) @ root");
+
+        // validate properties
+        List<String> properties = verifier.loadLines("target/pom.properties");
+        assertTrue(properties.contains("session.executionProperties.color1=green")); // CLI only
+        assertTrue(properties.contains("session.executionProperties.color2=blue")); // both
+        assertTrue(properties.contains("session.executionProperties.color3=yellow")); // cmd.txt only
+    }
+}

its/core-it-suite/src/test/java/org/apache/maven/it/TestSuiteOrdering.java

@@ -100,6 +100,7 @@ public TestSuiteOrdering() {
          * the tests are to finishing. Newer tests are also more likely to fail, so this is
          * a fail fast technique as well.
          */
+        suite.addTestSuite(MavenITmng8594AtFileTest.class);
         suite.addTestSuite(MavenITmng8561SourceRootTest.class);
         suite.addTestSuite(MavenITmng8523ModelPropertiesTest.class);
         suite.addTestSuite(MavenITmng8527ConsumerPomTest.class);

its/core-it-suite/src/test/resources/mng-8594/cmd.txt

@@ -0,0 +1,3 @@
+validate
+-Dcolor2=gray
+-Dcolor3=yellow

its/core-it-suite/src/test/resources/mng-8594/pom.xml

@@ -0,0 +1,34 @@
+<?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 https://maven.apache.org/maven-v4_0_0.xsd">
+
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>org.apache.maven.it.mng8594</groupId>
+  <artifactId>root</artifactId>
+  <version>1.0.0</version>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.its.plugins</groupId>
+        <artifactId>maven-it-plugin-expression</artifactId>
+        <version>2.1-SNAPSHOT</version>
+        <configuration>
+          <outputFile>target/pom.properties</outputFile>
+          <expressions>
+            <expression>session/executionProperties</expression>
+          </expressions>
+        </configuration>
+        <executions>
+          <execution>
+            <id>eval</id>
+            <goals>
+              <goal>eval</goal>
+            </goals>
+            <phase>validate</phase>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>