Maintenance on jsonexample (#205)

jsonexample/android/app/build.gradle

@@ -11,11 +11,26 @@ if (flutterRoot == null) {
     throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
 }
 
+def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
+if (flutterVersionCode == null) {
+    flutterVersionCode = '1'
+}
+
+def flutterVersionName = localProperties.getProperty('flutter.versionName')
+if (flutterVersionName == null) {
+    flutterVersionName = '1.0'
+}
+
 apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
-    compileSdkVersion 27
+    compileSdkVersion 28
+
+    sourceSets {
+        main.java.srcDirs += 'src/main/kotlin'
+    }
 
     lintOptions {
         disable 'InvalidPackage'
@@ -23,12 +38,12 @@ android {
 
     defaultConfig {
         // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
-        applicationId "com.google.example.jsonexample"
+        applicationId "dev.flutter.example.jsonexample"
         minSdkVersion 16
-        targetSdkVersion 27
-        versionCode 1
-        versionName "1.0"
-        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+        targetSdkVersion 28
+        versionCode flutterVersionCode.toInteger()
+        versionName flutterVersionName
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }
 
     buildTypes {
@@ -45,7 +60,8 @@ flutter {
 }
 
 dependencies {
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
     testImplementation 'junit:junit:4.12'
-    androidTestImplementation 'com.android.support.test:runner:1.0.1'
-    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
+    androidTestImplementation 'androidx.test:runner:1.1.1'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
 }