title: AccessibilityNodeInfo nodeInfo = event.getSource() always returns null
body: <p>I'm trying to use AccessibilityNodeInfo but when I use event.getSource()  it always returns null, I try to read the editbox of the browsers here is my codes: </p>
  
  <pre><code>public class MainActivity extends Activity {
  static final String TAG = "RecorderService";
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      Intent i = new Intent(this, RecorderService.class);
      startService(i);
  }}
  </code></pre>
  
  <p>accessibilityServicecode which acts as a service:</p>
  
  <pre><code>public class RecorderService extends AccessibilityService {
  
  static final String TAG = "RecorderService";
  
  private String getEventType(AccessibilityEvent event) {
      switch (event.getEventType()) {
          case AccessibilityEvent.TYPE_NOTIFICATION_STATE_CHANGED:
              return "TYPE_NOTIFICATION_STATE_CHANGED";
          case AccessibilityEvent.TYPE_VIEW_CLICKED:
              return "TYPE_VIEW_CLICKED";
          case AccessibilityEvent.TYPE_VIEW_FOCUSED:
              return "TYPE_VIEW_FOCUSED";
          case AccessibilityEvent.TYPE_VIEW_LONG_CLICKED:
              return "TYPE_VIEW_LONG_CLICKED";
          case AccessibilityEvent.TYPE_VIEW_SELECTED:
              return "TYPE_VIEW_SELECTED";
          case AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED:
              return "TYPE_WINDOW_STATE_CHANGED";
          case AccessibilityEvent.TYPE_VIEW_TEXT_CHANGED:
              return "TYPE_VIEW_TEXT_CHANGED";
      }
      return "default";
  }
  
  private String getEventText(AccessibilityEvent event) {
      StringBuilder sb = new StringBuilder();
      for (CharSequence s : event.getText()) {
          sb.append(s);
      }
      return sb.toString();
  }
  @Override
  public void onAccessibilityEvent(AccessibilityEvent event) {
  
      AccessibilityNodeInfo source = null;
      if (android.os.Build.VERSION.SDK_INT &gt;= android.os.Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
          source = event.getSource();
          Log.v(TAG, "Source Accessibility node info: " + source);
      }
  
      Log.v(TAG, String.format(
              "onAccessibilityEvent: [type] %s [class] %s [package] %s [time] %s [text] %s",
              getEventType(event), event.getClassName(), event.getPackageName(),
              event.getEventTime(), getEventText(event)));
  }
  @Override
  public void onInterrupt() {
      Log.v(TAG, "onInterrupt");
  }
  
  @Override
  protected void onServiceConnected() {
      super.onServiceConnected();
      Log.v(TAG, "***********onServiceConnected");
      AccessibilityServiceInfo info = new AccessibilityServiceInfo();
      info.flags = AccessibilityServiceInfo.DEFAULT |
              AccessibilityServiceInfo.FLAG_RETRIEVE_INTERACTIVE_WINDOWS |
              AccessibilityServiceInfo.FLAG_REQUEST_ENHANCED_WEB_ACCESSIBILITY |
              AccessibilityServiceInfo.FLAG_INCLUDE_NOT_IMPORTANT_VIEWS |
              AccessibilityServiceInfo.FLAG_REPORT_VIEW_IDS;
      info.eventTypes = AccessibilityEvent.TYPES_ALL_MASK;
      info.feedbackType = AccessibilityServiceInfo.FEEDBACK_GENERIC;
      setServiceInfo(info);}}
  </code></pre>
  
  <p>acessbibility.xml:</p>
  
  <pre><code>&lt;accessibility-service xmlns:android="http://schemas.android.com/apk/res/android"
  android:accessibilityEventTypes="typeWindowStateChanged|typeViewHoverEnter|typeViewHoverExit|typeWindowContentChanged"
  android:accessibilityFeedbackType="feedbackSpoken"
  android:accessibilityFlags="flagDefault|flagIncludeNotImportantViews|flagRequestTouchExplorationMode|flagRequestEnhancedWebAccessibility|flagReportViewIds|flagRequestFilterKeyEvents"
  android:canRetrieveWindowContent="true"
  android:canRequestTouchExplorationMode="true"
  android:canRequestFilterKeyEvents="true"
  android:canRequestEnhancedWebAccessibility="true"
  android:settingsActivity="com.recorderservice"
  /&gt;
  </code></pre>