title: Error in react-native-navigation after updating MainApplication.java
body: <p>I installed react native navigation and followed the steps. Works on iOS. Doesn't on android. 
  I get this error when I run react-native run-android, after updating "MainApplication.java" file:</p>
  
  <blockquote>
    <blockquote>
      <p>Task :app:compileDebugJavaWithJavac FAILED</p>
    </blockquote>
    
    <p>Deprecated Gradle features were used in this build, making it
    incompatible with G radle 6.0. Use '--warning-mode all' to show the
    individual deprecation warnings. See
    <a href="https://docs.gradle.org/5.5/userguide/command_line_interface.html#sec:command_line_warnings" rel="nofollow noreferrer">https://docs.gradle.org/5.5/userguide/command_line_interface.html#sec:command_line_warnings</a>
    43 actionable tasks: 2 executed, 41 up-to-date
    /home/wilux/rnApp/android/app/src/main/java/com/rnApp/MainApplication.java:
    17: error: MainApplication is not abstract and does not override
    abstract method  createAdditionalReactPackages() in
    NavigationApplication public class MainApplication extends
    NavigationApplication {
           ^ 1 error</p>
    
    <p>FAILURE: Build failed with an exception.</p>
    
    <ul>
    <li><p>What went wrong: Execution failed for task ':app:compileDebugJavaWithJavac'.</p>
    
    <blockquote>
      <p>Compilation failed; see the compiler error output for details.</p>
    </blockquote></li>
    <li><p>Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.</p></li>
    <li><p>Get more help at <a href="https://help.gradle.org" rel="nofollow noreferrer">https://help.gradle.org</a></p></li>
    </ul>
    
    <p>BUILD FAILED in 4s</p>
    
    <p>error Failed to install the app. Make sure you have the Android
    development environment set up:
    <a href="https://facebook.github.io/react-native/docs/getting-started.html#android-development-environment" rel="nofollow noreferrer">https://facebook.github.io/react-native/docs/getting-started.html#android-development-environment</a>.
    Run CLI with --verbose flag for more details. Error: Command failed:
    ./gradlew app:installDebug -PreactNativeDevServerPort=8081
    /home/wilux/rnApp/android/app/src/main/java/com/rnApp/MainApplication.java:17:
    error: MainApplication is not abstract and does not override abstract
    method createAdditionalReactPackages() in NavigationApplication public
    class MainApplication extends NavigationApplication {
           ^ 1 error</p>
    
    <p>FAILURE: Build failed with an exception.</p>
    
    <ul>
    <li><p>What went wrong: Execution failed for task ':app:compileDebugJavaWithJavac'.</p>
    
    <blockquote>
      <p>Compilation failed; see the compiler error output for details.</p>
    </blockquote></li>
    <li><p>Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.</p></li>
    <li><p>Get more help at <a href="https://help.gradle.org" rel="nofollow noreferrer">https://help.gradle.org</a></p></li>
    </ul>
    
    <p>BUILD FAILED in 4s</p>
  
  <pre><code>at checkExecSyncError (child_process.js:610:11)
  at execFileSync (child_process.js:628:15)
  at runOnAllDevices (/home/wilux/rnApp/node_modules/@react-native-community/cli-platform-android/build/commands/runAndroid/runOnAllDevices.js:94:39)
  at buildAndRun (/home/wilux/rnApp/node_modules/@react-native-community/cli-platform-android/build/commands/runAndroid/index.js:158:41)
  at /home/wilux/rnApp/node_modules/@react-native-community/cli-platform-android/build/commands/runAndroid/index.js:125:12
  at processTicksAndRejections (internal/process/task_queues.js:97:5)
  at async Command.handleAction (/home/wilux/rnApp/node_modules/react-native/node_modules/@react-native-community/cli/build/index.js:164:9)
  </code></pre>
  </blockquote>
  
  <p>The strange thing is that it worked when I update "android/build.gradle" and "android/app/build.gradle" files ! </p>
  
  <p>Here is the updated file (MainApplication.java) :</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>package com.rnApp;
  
  import android.app.Application;
  import android.content.Context;
  import com.facebook.react.PackageList;
  import com.facebook.react.ReactApplication;
  import com.oblador.vectoricons.VectorIconsPackage;
  import com.facebook.react.ReactNativeHost;
  import com.facebook.react.ReactPackage;
  import com.facebook.soloader.SoLoader;
  import com.reactnativenavigation.NavigationApplication;
  import com.reactnativenavigation.react.NavigationReactNativeHost;
  import com.reactnativenavigation.react.ReactGateway;
  import java.lang.reflect.InvocationTargetException;
  import java.util.List;
  
  public class MainApplication extends NavigationApplication {
      
          @Override
          protected ReactGateway createReactGateway() {
              ReactNativeHost host = new NavigationReactNativeHost(this, isDebug(), createAdditionalReactPackages()) {
                  @Override
                  protected String getJSMainModuleName() {
                      return "index";
                  }
              };
              return new ReactGateway(this, isDebug(), host);
          }
      
          @Override
          public boolean isDebug() {
              return BuildConfig.DEBUG;
          }
      
          protected List&lt;ReactPackage&gt; getPackages() {
              // Add additional packages you require here
              // No need to add RnnPackage and MainReactPackage
              return Arrays.&lt;ReactPackage&gt;asList(
                  // eg. new VectorIconsPackage()
              );
          }
      
          @Override
          public List&lt;ReactPackage&gt; createAdditionalReactPackages() {
              return getPackages();
          }
      }</code></pre>
  </div>
  </div>
  </p>