title: Flutter fail to run app on device import androidx.annotation.Nullable
body: <pre><code>Initializing gradle...
  Resolving dependencies...
  Gradle task 'assembleDebug'...
  registerResGeneratingTask is deprecated, use registerGeneratedResFolders(FileCollection)
  registerResGeneratingTask is deprecated, use registerGeneratedResFolders(FileCollection)
  registerResGeneratingTask is deprecated, use registerGeneratedResFolders(FileCollection)
  registerResGeneratingTask is deprecated, use registerGeneratedResFolders(FileCollection)
  registerResGeneratingTask is deprecated, use registerGeneratedResFolders(FileCollection)
  /Users/ipatel/Documents/AAAA/FlutterSetup/flutter/.pub-cache/hosted/pub.dartlang.org/cloud_firestore-0.9.0/android/src/main/java/io/flutter/plugins/firebase/cloudfirestore/CloudFirestorePlugin.java:9: error: cannot find symbol
  import androidx.annotation.NonNull;
                            ^
    symbol:   class NonNull
    location: package androidx.annotation
  /Users/ipatel/Documents/AAAA/FlutterSetup/flutter/.pub-cache/hosted/pub.dartlang.org/cloud_firestore-0.9.0/android/src/main/java/io/flutter/plugins/firebase/cloudfirestore/CloudFirestorePlugin.java:10: error: cannot find symbol
  import androidx.annotation.Nullable;
                            ^
    symbol:   class Nullable
    location: package androidx.annotation
  /Users/ipatel/Documents/AAAA/FlutterSetup/flutter/.pub-cache/hosted/pub.dartlang.org/cloud_firestore-0.9.0/android/src/main/java/io/flutter/plugins/firebase/cloudfirestore/CloudFirestorePlugin.java:253: error: cannot find symbol
            public void onFailure(@NonNull Exception e) {
                                   ^
    symbol: class NonNull
  /Users/ipatel/Documents/AAAA/FlutterSetup/flutter/.pub-cache/hosted/pub.dartlang.org/cloud_firestore-0.9.0/android/src/main/java/io/flutter/plugins/firebase/cloudfirestore/CloudFirestorePlugin.java:274: error: cannot find symbol
                      public Void apply(@NonNull Transaction transaction)
                                         ^
    symbol: class NonNull
  /Users/ipatel/Documents/AAAA/FlutterSetup/flutter/.pub-cache/hosted/pub.dartlang.org/cloud_firestore-0.9.0/android/src/main/java/io/flutter/plugins/firebase/cloudfirestore/CloudFirestorePlugin.java:272: error: cannot find symbol
                      @Nullable
                       ^
    symbol: class Nullable
  /Users/ipatel/Documents/AAAA/FlutterSetup/flutter/.pub-cache/hosted/pub.dartlang.org/cloud_firestore-0.9.0/android/src/main/java/io/flutter/plugins/firebase/cloudfirestore/CloudFirestorePlugin.java:503: error: cannot find symbol
                      public void onFailure(@NonNull Exception e) {
                                             ^
    symbol: class NonNull
  /Users/ipatel/Documents/AAAA/FlutterSetup/flutter/.pub-cache/hosted/pub.dartlang.org/cloud_firestore-0.9.0/android/src/main/java/io/flutter/plugins/firebase/cloudfirestore/CloudFirestorePlugin.java:558: error: cannot find symbol
                      public void onFailure(@NonNull Exception e) {
                                             ^
    symbol: class NonNull
  7 errors
  
  FAILURE: Build failed with an exception.
  
  * What went wrong:
  Execution failed for task ':cloud_firestore:compileDebugJavaWithJavac'.
  &gt; Compilation failed; see the compiler error output for details.
  
  * 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.
  
  * Get more help at https://help.gradle.org
  
  BUILD FAILED in 4s
  Finished with error: Gradle task assembleDebug failed with exit code 1
  </code></pre>
  
  <p>Don't know why Above Error found? I just try to connect device in my system and run. </p>
  
  <p>Perviously I tried to run app on device by VS Code without Android Studio Installed. So I have followed <a href="https://medium.com/@aubykhan/setting-up-flutter-without-android-studio-6f7abdeb353c" rel="noreferrer">https://medium.com/@aubykhan/setting-up-flutter-without-android-studio-6f7abdeb353c</a> this tutorial and manually installed Gradle by terminal.</p>
  
  <p>Below are some history of my terminal:</p>
  
  <blockquote>
    <p>431  brew install gradle<br>
      432  brew cask install java<br>
      433  brew install gradle<br>
      434  flutter config --gradle-dir /usr/local/opt/gradle<br>
      435  flutter --version<br>
      436  clear<br>
      437  flutter doctor<br>
      438  sdkmanager "system-images;android-21;default;x86_64"<br>
      439  vi ~/.bash_profile<br>
      440  Open $HOME/.bash_profile       </p>
  </blockquote>
  
  <p>I thought issue might be is system found two path of Gradle or issue are others? Don't know but how can I figure out this issue ?</p>