Resolve "Fix build application package"

Closes #2 (closed)

android/app/build.gradle

@@ -32,6 +32,12 @@ if (appVersionName == null) {
 apply plugin: 'com.android.application'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
+def keystoreProperties = new Properties()
+def keystorePropertiesFile = rootProject.file('key.properties')
+if (keystorePropertiesFile.exists()) {
+    keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
+}
+
 android {
     compileSdkVersion 30