moduleNAME?

android/app/src/main/java/com/reactnativenavigation/NavigationApplication.java

 
 import android.app.Application;
 import android.os.Handler;
+import android.support.annotation.NonNull;
 
 import com.facebook.react.ReactPackage;
 import com.facebook.react.shell.MainReactPackage;
         List<ReactPackage> list = Arrays.asList(
                 new MainReactPackage(),
                 new NavigationReactPackage());
-        list.addAll(createAdditionalReactPackages());
+        addAdditionalReactPackagesIfNeeded(list);
         return list;
     }
 
+    private void addAdditionalReactPackagesIfNeeded(List<ReactPackage> list) {
+        List<ReactPackage> additionalReactPackages = createAdditionalReactPackages();
+
+        for (ReactPackage reactPackage : additionalReactPackages) {
+            if (reactPackage instanceof MainReactPackage)
+                throw new RuntimeException("Do not create a new MainReactPackage. This is created for you.");
+            if (reactPackage instanceof NavigationReactPackage)
+                throw new RuntimeException("Do not create a new NavigationReactPackage. This is created for you.");
+        }
+
+        list.addAll(additionalReactPackages);
+    }
+
+    public String getJsEntryFileName() {
+        return "index.android";
+    }
+
+    public String getBundleAssetName() {
+        return "index.android.bundle";
+    }
+
     public abstract boolean isDebug();
 
+    @NonNull
     public abstract List<ReactPackage> createAdditionalReactPackages();
+
 }

android/app/src/main/java/com/reactnativenavigation/layouts/ScreenLayout.java

         setNavigationBarColor(styleParams.navigationBarColor);
         topBar.setTitleBarVisibility(styleParams.titleBarHidden);
         topBar.setVisibility(styleParams.topBarHidden ? GONE : VISIBLE);
-
     }
 
     @TargetApi(Build.VERSION_CODES.LOLLIPOP)

android/app/src/main/java/com/reactnativenavigation/react/NavigationReactInstance.java

     private ReactInstanceManager createReactInstanceManager(final ReactContextCreator reactContextCreator) {
         ReactInstanceManager.Builder builder = ReactInstanceManager.builder()
                 .setApplication(NavigationApplication.instance)
-                .setJSMainModuleName("index.android")
-                .setBundleAssetName("index.android.bundle")
+                .setJSMainModuleName(NavigationApplication.instance.getJsEntryFileName())
+                .setBundleAssetName(NavigationApplication.instance.getBundleAssetName())
                 .setUseDeveloperSupport(NavigationApplication.instance.isDebug())
                 .setInitialLifecycleState(LifecycleState.BEFORE_RESUME);
 

android/app/src/main/java/com/reactnativenavigation/views/ContentView.java

 import android.os.Bundle;
 import android.view.ViewGroup;
 
+import com.facebook.react.ReactInstanceManager;
 import com.facebook.react.ReactRootView;
 import com.reactnativenavigation.NavigationApplication;
 import com.reactnativenavigation.react.ReactViewHacks;
     }
 
     public void init() {
-        startReactApplication(NavigationApplication.instance.getNavigationReactInstance().getReactInstanceManager(), screenId, passProps);
+        ReactInstanceManager react = NavigationApplication.instance.getNavigationReactInstance().getReactInstanceManager();
+        startReactApplication(react, screenId, passProps);
         new ScrollViewAttacher(this, scrollListener).attach();
     }