Gradle build now works correctly

mobile/com.sap.sailing.racecommittee.app/res/menu/options_menu.xml

@@ -1,15 +1,16 @@
 <?xml version="1.0" encoding="utf-8"?>
-<menu xmlns:android="http://schemas.android.com/apk/res/android">
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
     <item android:id="@+id/options_menu_reload"
           android:icon="@drawable/ic_menu_info_details"
           android:title="@string/options_menu_reload"
-          android:showAsAction="" />
+          app:showAsAction="" />
     <item android:id="@+id/options_menu_settings"
           android:icon="@drawable/settings_grey"
           android:title="@string/options_menu_settings"
-          android:showAsAction="" />
+          app:showAsAction="" />
     <item android:id="@+id/options_menu_info"
           android:icon="@drawable/ic_menu_info_details"
           android:title="@string/options_menu_info"
-          android:showAsAction="" />
+          app:showAsAction="" />
 </menu>

mobile/com.sap.sailing.racecommittee.app/res/values/strings.xml

@@ -2,6 +2,7 @@
 <resources xmlns:tools="http://schemas.android.com/tools">
 
     <string-array name="empty_array" tools:ignore="UnusedResources" />
+    <string name="empty"></string>
 
     <string name="running_on_course">(on course %s)</string>
     <string name="course_design_number_waypoints">Course has %s waypoints</string>