added tweaks for firebase integration and cleared some build warnings.

build.gradle

@@ -7,10 +7,14 @@ buildscript {
     dependencies {
         classpath 'com.android.tools.build:gradle:3.6.3'
         classpath 'org.greenrobot:greendao-gradle-plugin:3.3.0' // add plugin
+        classpath 'com.google.gms:google-services:4.3.3' //added gms support
+        classpath 'com.google.firebase:firebase-crashlytics-gradle:2.2.0'
+
     }
 }
 apply plugin: 'com.android.application'
 apply plugin: 'org.greenrobot.greendao'
+apply plugin: 'com.google.firebase.crashlytics'
 
 allprojects {
     repositories {

google-services.json

@@ -0,0 +1,40 @@
+{
+  "project_info": {
+    "project_number": "283609891050",
+    "firebase_url": "https://hostage-4f7c7.firebaseio.com",
+    "project_id": "hostage-4f7c7",
+    "storage_bucket": "hostage-4f7c7.appspot.com"
+  },
+  "client": [
+    {
+      "client_info": {
+        "mobilesdk_app_id": "1:283609891050:android:c9df120509b30ca36e9793",
+        "android_client_info": {
+          "package_name": "de.tudarmstadt.informatik.hostage"
+        }
+      },
+      "oauth_client": [
+        {
+          "client_id": "283609891050-36dl28rq07gt758o64dotvfceotf9deg.apps.googleusercontent.com",
+          "client_type": 3
+        }
+      ],
+      "api_key": [
+        {
+          "current_key": "AIzaSyD0RyNSaOfTPFui8xfnibzPI8qt0bklFXQ"
+        }
+      ],
+      "services": {
+        "appinvite_service": {
+          "other_platform_oauth_client": [
+            {
+              "client_id": "283609891050-36dl28rq07gt758o64dotvfceotf9deg.apps.googleusercontent.com",
+              "client_type": 3
+            }
+          ]
+        }
+      }
+    }
+  ],
+  "configuration_version": "1"
+}

gradle.properties

@@ -1,3 +1,4 @@
 android.useAndroidX=true
 android.enableJetifier=true
-android.enableUnitTestBinaryResources=true
+#android.enableUnitTestBinaryResources=true
+android.debug.obsoleteApi=true