Load Android Gradle Plugin conditionally

Author: SaeedZhiany

templates/android.js

@@ -1,14 +1,18 @@
 module.exports = platform => [{
   name: () => `${platform}/build.gradle`,
   content: ({ packageIdentifier }) => `buildscript {
-    repositories {
-        jcenter()
-    }
+    // The Android Gradle plugin is only required when opening the android folder stand-alone.
+    // This avoids unnecessary downloads and potential conflicts when the library is included as a
+    // module dependency in an application project.
+    if (project == rootProject) {
+        repositories {
+            google()
+            jcenter()
+        }
 
-    dependencies {
-        // Matches the RN Hello World template
-        // https://github.com/facebook/react-native/blob/1e8f3b11027fe0a7514b4fc97d0798d3c64bc895/local-cli/templates/HelloWorld/android/build.gradle#L8
-        classpath 'com.android.tools.build:gradle:2.2.3'
+        dependencies {
+            classpath("com.android.tools.build:gradle:3.5.3")
+        }
     }
 }
 
@@ -19,18 +23,13 @@ def safeExtGet(prop, fallback) {
     rootProject.ext.has(prop) ? rootProject.ext.get(prop) : fallback
 }
 
-def DEFAULT_COMPILE_SDK_VERSION = 27
-def DEFAULT_BUILD_TOOLS_VERSION = "27.0.3"
-def DEFAULT_MIN_SDK_VERSION = 16
-def DEFAULT_TARGET_SDK_VERSION = 27
-
 android {
-  compileSdkVersion safeExtGet('compileSdkVersion', DEFAULT_COMPILE_SDK_VERSION)
-  buildToolsVersion safeExtGet('buildToolsVersion', DEFAULT_BUILD_TOOLS_VERSION)
+  compileSdkVersion safeExtGet('compileSdkVersion', 28)
+  buildToolsVersion safeExtGet('buildToolsVersion', '28.0.3')
 
   defaultConfig {
-    minSdkVersion safeExtGet('minSdkVersion', DEFAULT_MIN_SDK_VERSION)
-    targetSdkVersion safeExtGet('targetSdkVersion', DEFAULT_TARGET_SDK_VERSION)
+    minSdkVersion safeExtGet('minSdkVersion', 16)
+    targetSdkVersion safeExtGet('targetSdkVersion', 28)
     versionCode 1
     versionName "1.0"
   }
@@ -40,6 +39,7 @@ android {
 }
 
 repositories {
+	google()
     maven {
         // All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
         // Matches the RN Hello World template
@@ -50,7 +50,7 @@ repositories {
 }
 
 dependencies {
-    compile 'com.facebook.react:react-native:+'
+    implementation 'com.facebook.react:react-native:+'
 }
 
 def configureReactNativePom(def pom) {