activating highest version in duplicate dependencies.

source/AndroidResolver/src/GradleResolver.cs

@@ -105,6 +105,15 @@ private void LogMissingDependenciesError(List<string> missingArtifacts) {
             }
         }
 
+        /// <summary>
+        /// Get package spec from a dependency.
+        /// </summary>
+        /// <param name="dependency">Dependency instance to query for package spec.</param>
+        internal static string DependencyToPackageSpec(Dependency dependency) {
+            return dependency.Version.ToUpper() == "LATEST" ?
+                dependency.VersionlessKey + ":+" : dependency.Key;
+        }
+
         /// <summary>
         /// From a list of dependencies generate a list of Maven / Gradle / Ivy package spec
         /// strings.
@@ -116,8 +125,7 @@ internal static Dictionary<string, string> DependenciesToPackageSpecs(
             var sourcesByPackageSpec = new Dictionary<string, string>();
             foreach (var dependency in dependencies) {
                 // Convert the legacy "LATEST" version spec to a Gradle version spec.
-                var packageSpec = dependency.Version.ToUpper() == "LATEST" ?
-                    dependency.VersionlessKey + ":+" : dependency.Key;
+                var packageSpec = DependencyToPackageSpec(dependency);
                 var source = CommandLine.SplitLines(dependency.CreatedBy)[0];
                 string sources;
                 if (sourcesByPackageSpec.TryGetValue(packageSpec, out sources)) {

source/AndroidResolver/src/PlayServicesResolver.cs

@@ -2191,15 +2191,56 @@ internal static IList<string> GradleDependenciesLines(
                 // https://docs.gradle.org/3.4/release-notes.html#the-java-library-plugin
                 // https://developer.android.com/studio/releases/gradle-plugin#3-0-0
                 var version = GradleVersion;
+                var versionComparer = new Dependency.VersionComparer();
                 var includeStatement =
                     !String.IsNullOrEmpty(version) &&
-                    (new Dependency.VersionComparer()).Compare("3.4", version) >= 0 ?
+                    versionComparer.Compare("3.4", version) >= 0 ?
                     "implementation" : "compile";
                 if (includeDependenciesBlock) lines.Add("dependencies {");
+                // Build a map of dependencies with the max version of that dependency.
+                // If different packages have different versions of the same dependency,
+                // we want to activate only the highest version but still include the
+                // other versions as commented out dependency lines.
+                var dependenciesMaxVersions = new Dictionary<string, Dependency>();
+                // Maintain a set of packages which we want to comment out.
+                HashSet<string> packageSpecStringsToComment = new HashSet<string>();
+                foreach( var dependency in dependencies) {
+                    Dependency dependencyMaxVersion;
+                    if (dependenciesMaxVersions.TryGetValue(dependency.VersionlessKey, out dependencyMaxVersion)){
+                        if(versionComparer.Compare(dependency.Version, dependencyMaxVersion.Version) < 0) {
+                            dependenciesMaxVersions[dependency.VersionlessKey] = dependency;
+                            // We found a new larger version. Comment out older one
+                            // Build a single item list since `GetPackageSpecs`
+                            // accepts an IEnumerable type.
+                            var packageSpecString = GradleResolver.DependencyToPackageSpec(dependencyMaxVersion);
+                            packageSpecStringsToComment.Add(packageSpecString);
+                        }
+                        else {
+                            // Dependency version is smaller than current max.
+                            var packageSpecString = GradleResolver.DependencyToPackageSpec(dependency);
+                            packageSpecStringsToComment.Add(packageSpecString);
+                        }
+                    }
+                    else {
+                        // First time encountering this dependency.
+                        dependenciesMaxVersions[dependency.VersionlessKey] = dependency;
+                    }
+                }
                 foreach (var packageSpecAndSources in GetPackageSpecs(dependencies: dependencies)) {
-                    lines.Add(String.Format(
-                        "    {0} '{1}' // {2}", includeStatement, packageSpecAndSources.Key,
-                        packageSpecAndSources.Value));
+                    string line = "    ";
+                    if (packageSpecStringsToComment.Contains(packageSpecAndSources.Key)) {
+                        PlayServicesResolver.Log(
+                            String.Format(
+                                "Ignoring duplicate package {0} with older version.",
+                                 packageSpecAndSources.Key),
+                                 level: LogLevel.Info
+                            );
+                        line += "// ";
+                    }
+                    line += String.Format(
+                            "{0} '{1}' // {2}", includeStatement, packageSpecAndSources.Key,
+                            packageSpecAndSources.Value);
+                    lines.Add(line);
                 }
                 if (includeDependenciesBlock) lines.Add("}");
             }

source/AndroidResolver/test/AndroidResolverIntegrationTestsUnityProject/Assets/ExternalDependencyManager/Editor/TestAdditionalDuplicateDependencies.template

@@ -0,0 +1,13 @@
+<dependencies>
+  <androidPackages>
+    <!-- Duplicate entry for package with a different version (higher). -->
+    <androidPackage spec="com.google.android.gms:play-services-base:18.0.1" />
+    <!-- Duplicate entry for package with a different version (lower). -->
+    <androidPackage spec="com.google.android.gms:play-services-base:12.0.1" />
+    <!-- Duplicate entry for package with a different version (wildcard). -->
+    <androidPackage spec="com.google.firebase:firebase-app-unity:5.+"/>
+    <!-- Duplicate entry for package with the exact same version. -->
+    <androidPackage spec="com.android.support:support-annotations:26.1.0"/>
+  </androidPackages>
+</dependencies>
+

source/AndroidResolver/test/AndroidResolverIntegrationTestsUnityProject/ExpectedArtifacts/NoExport/GradleTemplateDuplicatePackages/mainTemplate.gradle

@@ -0,0 +1,104 @@
+// GENERATED BY UNITY. REMOVE THIS COMMENT TO PREVENT OVERWRITING WHEN EXPORTING AGAIN
+
+buildscript {
+    repositories {
+        jcenter()
+        google()
+    }
+
+    dependencies {
+        classpath 'com.android.tools.build:gradle:3.0.1'
+    }
+}
+
+allprojects {
+    repositories {
+        flatDir {
+            dirs 'libs'
+        }
+    }
+}
+
+// Android Resolver Repos Start
+([rootProject] + (rootProject.subprojects as List)).each { project ->
+    project.repositories {
+        def unityProjectPath = $/file:///**DIR_UNITYPROJECT**/$.replace("\\", "/")
+        maven {
+            url "https://maven.google.com"
+        }
+        maven {
+            url "file:///my/nonexistant/test/repo" // Assets/ExternalDependencyManager/Editor/TestDependencies.xml:17
+        }
+        maven {
+            url (unityProjectPath + "/project_relative_path/repo") // Assets/ExternalDependencyManager/Editor/TestDependencies.xml:17
+        }
+        maven {
+            url (unityProjectPath + "/Assets/GeneratedLocalRepo/Firebase/m2repository") // Assets/ExternalDependencyManager/Editor/TestDependencies.xml:10
+        }
+        mavenLocal()
+        jcenter()
+        mavenCentral()
+    }
+}
+// Android Resolver Repos End
+apply plugin: 'com.android.application'
+
+dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+// Android Resolver Dependencies Start
+    compile 'com.android.support:support-annotations:26.1.0' // Assets/ExternalDependencyManager/Editor/TestDependencies.xml:4
+    // compile 'com.google.android.gms:play-services-base:12.0.1' // Assets/ExternalDependencyManager/Editor/TestAdditionalDuplicateDependencies.xml:6
+    // compile 'com.google.android.gms:play-services-base:15.0.1' // Assets/ExternalDependencyManager/Editor/TestAdditionalDependencies.xml:3
+    compile 'com.google.android.gms:play-services-base:18.0.1' // Assets/ExternalDependencyManager/Editor/TestAdditionalDuplicateDependencies.xml:4
+    // compile 'com.google.firebase:firebase-app-unity:5.+' // Assets/ExternalDependencyManager/Editor/TestAdditionalDuplicateDependencies.xml:8
+    compile 'com.google.firebase:firebase-app-unity:5.1.1' // Assets/ExternalDependencyManager/Editor/TestDependencies.xml:10
+    compile 'com.google.firebase:firebase-common:16.0.0' // Google.AndroidResolverIntegrationTests.SetupDependencies
+    compile 'org.test.psr:classifier:1.0.1:foo@aar' // Assets/ExternalDependencyManager/Editor/TestDependencies.xml:12
+// Android Resolver Dependencies End
+**DEPS**}
+
+// Android Resolver Exclusions Start
+android {
+  packagingOptions {
+      exclude ('lib/unsupported/libFirebaseCppApp-5.1.1.so')
+  }
+}
+// Android Resolver Exclusions End
+android {
+    compileSdkVersion **APIVERSION**
+    buildToolsVersion '**BUILDTOOLS**'
+
+    defaultConfig {
+        minSdkVersion **MINSDKVERSION**
+        targetSdkVersion **TARGETSDKVERSION**
+        applicationId '**APPLICATIONID**'
+        ndk {
+            abiFilters **ABIFILTERS**
+        }
+        versionCode **VERSIONCODE**
+        versionName '**VERSIONNAME**'
+    }
+
+    lintOptions {
+        abortOnError false
+    }
+
+    aaptOptions {
+        noCompress '.unity3d', '.ress', '.resource', '.obb'**STREAMING_ASSETS**
+    }**SIGN**
+
+    buildTypes {
+        debug {
+            minifyEnabled **MINIFY_DEBUG**
+            useProguard **PROGUARD_DEBUG**
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-unity.txt'**USER_PROGUARD**
+            jniDebuggable true
+        }
+        release {
+            minifyEnabled **MINIFY_RELEASE**
+            useProguard **PROGUARD_RELEASE**
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-unity.txt'**USER_PROGUARD****SIGNCONFIG**
+        }
+    }**PACKAGING_OPTIONS****SPLITS**
+**BUILT_APK_LOCATION**
+}**SPLITS_VERSION_CODE****SOURCE_BUILD_SETUP**

source/AndroidResolver/test/AndroidResolverIntegrationTestsUnityProject/ExpectedArtifacts/NoExport/GradleTemplateDuplicatePackages/mainTemplateDISABLED.gradle

@@ -0,0 +1,65 @@
+// GENERATED BY UNITY. REMOVE THIS COMMENT TO PREVENT OVERWRITING WHEN EXPORTING AGAIN
+
+buildscript {
+    repositories {
+        jcenter()
+        google()
+    }
+
+    dependencies {
+        classpath 'com.android.tools.build:gradle:3.0.1'
+    }
+}
+
+allprojects {
+    repositories {
+        flatDir {
+            dirs 'libs'
+        }
+    }
+}
+
+apply plugin: 'com.android.application'
+
+dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+**DEPS**}
+
+android {
+    compileSdkVersion **APIVERSION**
+    buildToolsVersion '**BUILDTOOLS**'
+
+    defaultConfig {
+        minSdkVersion **MINSDKVERSION**
+        targetSdkVersion **TARGETSDKVERSION**
+        applicationId '**APPLICATIONID**'
+        ndk {
+            abiFilters **ABIFILTERS**
+        }
+        versionCode **VERSIONCODE**
+        versionName '**VERSIONNAME**'
+    }
+
+    lintOptions {
+        abortOnError false
+    }
+
+    aaptOptions {
+        noCompress '.unity3d', '.ress', '.resource', '.obb'**STREAMING_ASSETS**
+    }**SIGN**
+
+    buildTypes {
+        debug {
+            minifyEnabled **MINIFY_DEBUG**
+            useProguard **PROGUARD_DEBUG**
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-unity.txt'**USER_PROGUARD**
+            jniDebuggable true
+        }
+        release {
+            minifyEnabled **MINIFY_RELEASE**
+            useProguard **PROGUARD_RELEASE**
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-unity.txt'**USER_PROGUARD****SIGNCONFIG**
+        }
+    }**PACKAGING_OPTIONS****SPLITS**
+**BUILT_APK_LOCATION**
+}**SPLITS_VERSION_CODE****SOURCE_BUILD_SETUP**

source/AndroidResolver/test/src/AndroidResolverIntegrationTests.cs

@@ -44,6 +44,12 @@ public class AndroidResolverIntegrationTests {
     /// </summary>
     private const string ADDITIONAL_DEPENDENCIES_FILENAME = "TestAdditionalDependencies";
 
+    /// <summary>
+    /// The name of the file, without extension, that will serve as a template for dynamically
+    /// adding additional dependencies with a duplicate package with a different version.
+    /// </summary>
+    private const string ADDITIONAL_DUPLICATE_DEPENDENCIES_FILENAME = "TestAdditionalDuplicateDependencies";
+
     /// <summary>
     /// Disabled application Gradle template file.
     /// </summary>
@@ -129,6 +135,29 @@ public static void ConfigureTestCases() {
                             });
                     }
                 },
+                new IntegrationTester.TestCase {
+                    Name = "ResolveForGradleBuildSystemWithDuplicatePackages",
+                    Method = (testCase, testCaseComplete) => {
+                        ClearAllDependencies();
+                        SetupDependencies();
+                        // Add 2 additional dependency files (each file contains a single package
+                        // but with different versions).
+                        UpdateAdditionalDependenciesFile(true, ADDITIONAL_DEPENDENCIES_FILENAME);
+                        UpdateAdditionalDependenciesFile(true, ADDITIONAL_DUPLICATE_DEPENDENCIES_FILENAME);
+
+                        ResolveWithGradleTemplate(
+                            GRADLE_TEMPLATE_DISABLED,
+                            "ExpectedArtifacts/NoExport/GradleTemplateDuplicatePackages",
+                            testCase, testCaseComplete,
+                            otherExpectedFiles: new [] {
+                                "Assets/GeneratedLocalRepo/Firebase/m2repository/com/google/" +
+                                "firebase/firebase-app-unity/5.1.1/firebase-app-unity-5.1.1.aar" },
+                            filesToIgnore: new HashSet<string> {
+                                Path.GetFileName(GRADLE_TEMPLATE_LIBRARY_DISABLED),
+                                Path.GetFileName(GRADLE_TEMPLATE_PROPERTIES_DISABLED)
+                            });
+                    }
+                },
                 new IntegrationTester.TestCase {
                     Name = "ResolverForGradleBuildSystemWithTemplateUsingJetifier",
                     Method = (testCase, testCaseComplete) => {
@@ -474,7 +503,8 @@ private static void ClearAllDependencies() {
         GooglePlayServices.SettingsDialog.PatchPropertiesTemplateGradle = false;
 
         PlayServicesSupport.ResetDependencies();
-        UpdateAdditionalDependenciesFile(false);
+        UpdateAdditionalDependenciesFile(false, ADDITIONAL_DEPENDENCIES_FILENAME);
+        UpdateAdditionalDependenciesFile(false, ADDITIONAL_DUPLICATE_DEPENDENCIES_FILENAME);
     }
 
     /// <summary>
@@ -565,14 +595,18 @@ private static void CompareKeyValuePairLists(
     /// </summary>
     /// <param name="addDependencyFile">If true, will copy the template file to an XML file if it
     /// doesn't exist. If false, delete the XML file if it exists.</param>
-    private static void UpdateAdditionalDependenciesFile(bool addDependencyFile) {
+    /// <param name="filename">Name of the template file (without extension) to
+    /// create an XML from. </param>
+    private static void UpdateAdditionalDependenciesFile(
+            bool addDependencyFile,
+            string filename=ADDITIONAL_DEPENDENCIES_FILENAME) {
         string currentDirectory = Directory.GetCurrentDirectory();
         string editorPath = Path.Combine(currentDirectory,
                                          "Assets/ExternalDependencyManager/Editor/");
 
-        string templateFilePath = Path.Combine(editorPath, ADDITIONAL_DEPENDENCIES_FILENAME +
+        string templateFilePath = Path.Combine(editorPath, filename+
             ".template");
-        string xmlFilePath = Path.Combine(editorPath, ADDITIONAL_DEPENDENCIES_FILENAME + ".xml");
+        string xmlFilePath = Path.Combine(editorPath, filename+ ".xml");
         if (addDependencyFile && !File.Exists(xmlFilePath)) {
             if (!File.Exists(templateFilePath)) {
                 UnityEngine.Debug.LogError("Could not find file: " + templateFilePath);