title: QueryDocumentSnapshot cannot resolve
body: <p><code>QueryDocumentSnapshot</code> is not cannot be resolving. I tried to change the versions of <code>firebase-firestore</code> and <code>firebase-core</code> dependencies but still doesn't work.</p>
  
  <p>Here are the firebase imports:</p>
  
  <pre><code>import com.google.firebase.auth.FirebaseAuth;
  import com.google.firebase.auth.FirebaseUser;
  import com.google.firebase.firestore.DocumentReference;
  import com.google.firebase.firestore.FirebaseFirestore;
  import com.google.firebase.firestore.QueryDocumentSnapshot;
  import com.google.firebase.firestore.QuerySnapshot;
  </code></pre>
  
  <p>here are the dependencies</p>
  
  <pre><code>    implementation fileTree(include: ['*.jar'], dir: 'libs')
      implementation 'com.android.support:appcompat-v7:27.1.1'
      implementation 'com.android.support.constraint:constraint-layout:1.1.3'
      implementation 'com.google.firebase:firebase-auth:11.8.0'
      implementation 'de.hdodenhof:circleimageview:3.0.0'
      implementation 'com.github.bumptech.glide:glide:4.9.0'
      implementation 'com.google.firebase:firebase-database:11.8.0'
      implementation 'com.android.support:support-v4:26.1.0'
      annotationProcessor 'com.github.bumptech.glide:compiler:4.9.0'
      implementation 'com.getbase:floatingactionbutton:1.10.1'
      implementation 'com.theartofdev.edmodo:android-image-cropper:2.6.+'
      implementation 'com.google.firebase:firebase-storage:11.8.0'
      implementation 'com.google.firebase:firebase-firestore:11.8.0'
      implementation 'com.google.firebase:firebase-core:11.8.0'
  
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'com.android.support.test:runner:1.0.2'
      androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
      implementation 'com.android.support:design:27.1.1'
      implementation 'com.android.support:cardview-v7:27.1.1'
      implementation files('libs/activation.jar')
      implementation files('libs/additionnal.jar')
      implementation files('libs/mail.jar')
  
  </code></pre>