Implemented structure for push Notifications

android/app/build.gradle

@@ -23,6 +23,7 @@ if (flutterVersionName == null) {
 
 apply plugin: 'com.android.application'
 apply plugin: 'kotlin-android'
+apply plugin: 'com.google.gms.google-services'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
@@ -39,7 +40,7 @@ android {
         applicationId "eu.mhsl.marianum.mobile.client"
         // You can update the following values to match your application needs.
         // For more information, see: https://docs.flutter.dev/deployment/android#reviewing-the-build-configuration.
-        minSdkVersion flutter.minSdkVersion
+        minSdkVersion 19
         targetSdkVersion flutter.targetSdkVersion
         versionCode flutterVersionCode.toInteger()
         versionName flutterVersionName

android/app/google-services.json

@@ -0,0 +1,39 @@
+{
+  "project_info": {
+    "project_number": "522850592536",
+    "project_id": "marmobile-33b10",
+    "storage_bucket": "marmobile-33b10.appspot.com"
+  },
+  "client": [
+    {
+      "client_info": {
+        "mobilesdk_app_id": "1:522850592536:android:9a355c61e6f1b0f0c2606d",
+        "android_client_info": {
+          "package_name": "eu.mhsl.marianum.mobile.client"
+        }
+      },
+      "oauth_client": [
+        {
+          "client_id": "522850592536-5urolovocke0fmr7kpd0hqvfd3gft6qo.apps.googleusercontent.com",
+          "client_type": 3
+        }
+      ],
+      "api_key": [
+        {
+          "current_key": "AIzaSyAXo66A3jSBxnAYKgpUIfucidELoHw5W3M"
+        }
+      ],
+      "services": {
+        "appinvite_service": {
+          "other_platform_oauth_client": [
+            {
+              "client_id": "522850592536-5urolovocke0fmr7kpd0hqvfd3gft6qo.apps.googleusercontent.com",
+              "client_type": 3
+            }
+          ]
+        }
+      }
+    }
+  ],
+  "configuration_version": "1"
+}

android/app/src/main/java/io/flutter/app/FlutterMultiDexApplication.java

@@ -0,0 +1,25 @@
+// Generated file.
+//
+// If you wish to remove Flutter's multidex support, delete this entire file.
+//
+// Modifications to this file should be done in a copy under a different name
+// as this file may be regenerated.
+
+package io.flutter.app;
+
+import android.app.Application;
+import android.content.Context;
+import androidx.annotation.CallSuper;
+import androidx.multidex.MultiDex;
+
+/**
+ * Extension of {@link android.app.Application}, adding multidex support.
+ */
+public class FlutterMultiDexApplication extends Application {
+  @Override
+  @CallSuper
+  protected void attachBaseContext(Context base) {
+    super.attachBaseContext(base);
+    MultiDex.install(this);
+  }
+}

android/build.gradle

@@ -8,6 +8,7 @@ buildscript {
     dependencies {
         classpath 'com.android.tools.build:gradle:7.1.3'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+        classpath 'com.google.gms:google-services:4.3.15'
     }
 }