let the plugin's output generated in...

let the plugin's output generated in flutter/.android/plugins_build_output/${androidPlugin.name} (#94645)

packages/flutter_tools/gradle/module_plugin_loader.gradle

@@ -9,10 +9,12 @@ import groovy.json.JsonSlurper
 
 def moduleProjectRoot = project(':flutter').projectDir.parentFile.parentFile
 
+def object = null;
+String flutterModulePath = project(':flutter').projectDir.parentFile.getAbsolutePath()
 // Note: if this logic is changed, also change the logic in app_plugin_loader.gradle.
 def pluginsFile = new File(moduleProjectRoot, '.flutter-plugins-dependencies')
 if (pluginsFile.exists()) {
-    def object = new JsonSlurper().parseText(pluginsFile.text)
+    object = new JsonSlurper().parseText(pluginsFile.text)
     assert object instanceof Map
     assert object.plugins instanceof Map
     assert object.plugins.android instanceof List
@@ -35,6 +37,17 @@ if (pluginsFile.exists()) {
 
 gradle.getGradle().projectsLoaded { g ->
     g.rootProject.beforeEvaluate { p ->
+        p.subprojects { subproject ->
+            if (object != null && object.plugins != null && object.plugins.android != null
+                    && object.plugins.android.name.contains(subproject.name)) {
+                File androidPluginBuildOutputDir = new File(flutterModulePath + File.separator
+                        + "plugins_build_output" + File.separator + subproject.name);
+                if (!androidPluginBuildOutputDir.exists()) {
+                    androidPluginBuildOutputDir.mkdirs()
+                }
+                subproject.buildDir = androidPluginBuildOutputDir
+            }
+        }
         def _mainModuleName = binding.variables['mainModuleName']
         if (_mainModuleName != null && !_mainModuleName.empty) {
             p.ext.mainModuleName = _mainModuleName

packages/flutter_tools/test/integration.shard/android_plugin_new_output_dir_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:math';
+
+import 'package:file_testing/file_testing.dart';
+import 'package:flutter_tools/src/base/file_system.dart';
+import 'package:flutter_tools/src/base/io.dart';
+import 'package:flutter_tools/src/cache.dart';
+
+import '../src/common.dart';
+import 'test_utils.dart';
+
+void main() {
+
+  late Directory tempDir;
+
+  setUp(()  {
+    Cache.flutterRoot = getFlutterRoot();
+    tempDir = createResolvedTempDirectorySync('android_plugin_new_output_dir_test.');
+  });
+
+  tearDown(() async {
+    tryToDelete(tempDir);
+  });
+
+  test("error logged when plugin's build output dir was not private.", () async {
+    final String flutterBin = fileSystem.path.join(
+      getFlutterRoot(),
+      'bin',
+      'flutter',
+    );
+    // create flutter module project
+    ProcessResult result = processManager.runSync(<String>[
+      flutterBin,
+      ...getLocalEngineArguments(),
+      'create',
+      '--template=module',
+      'flutter_project'
+    ], workingDirectory: tempDir.path);
+
+    final String projectPath = fileSystem.path.join(tempDir.path, 'flutter_project');
+
+    final File modulePubspec = fileSystem.file(fileSystem.path.join(projectPath, 'pubspec.yaml'));
+    String pubspecContent = modulePubspec.readAsStringSync();
+    pubspecContent = pubspecContent.replaceFirst(
+      'dependencies:',
+      '''
+dependencies:
+  image_picker: 0.8.5+3''',
+    );
+    modulePubspec.writeAsStringSync(pubspecContent);
+
+    // Run flutter build apk to build module example project
+    result = processManager.runSync(<String>[
+      flutterBin,
+      ...getLocalEngineArguments(),
+      'build',
+      'aar',
+      '--target-platform=android-arm',
+    ], workingDirectory: projectPath);
+
+    log(result.exitCode);
+
+    // Check outputDir existed
+    final Directory outputDir = fileSystem.directory(fileSystem.path.join(
+        projectPath, '.android', 'plugins_build_output', 'image_picker_android'
+    ));
+    expect(outputDir, exists);
+
+  });
+}