title: populateView is called multiple times
body: <p><code>populateView</code> method of the <code>FirebaseListAdapter</code> class runs twice as often than expected and I don't know why. Here I put the database Firebase:</p>
  
  <p><img src="https://i.stack.imgur.com/DHaYR.jpg" alt="BBdd"></p>
  
  <p>This is the class that handles the data model</p>
  
  <pre><code>public class Chat {
  
  String name;
  String text;
  String uid;
  
  public Chat() {
  }
  
  public Chat(String name, String uid, String message) {
      this.name = name;
      this.text = message;
      this.uid = uid;
  }
  
  public String getName() {
      return name;
  }
  
  public String getUid() {
      return uid;
  }
  
  public String getText() {
      return text;
  }
  </code></pre>
  
  <p>And this is the main activity:</p>
  
  <pre><code>public class MainActivity extends AppCompatActivity {
  FirebaseListAdapter mAdapter;
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
  
      ListView messagesView = (ListView) findViewById(R.id.messages_list);
  
      DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
  
      mAdapter = new FirebaseListAdapter&lt;Chat&gt;(this, Chat.class, android.R.layout.two_line_list_item, ref) {
          @Override
          protected void populateView(View view, Chat chatMessage, int position) {
              ((TextView)view.findViewById(android.R.id.text1)).setText(chatMessage.getName());
              ((TextView)view.findViewById(android.R.id.text2)).setText(chatMessage.getText());
  
          }
      };
      messagesView.setAdapter(mAdapter);
  }
  </code></pre>