Hide Vr2dDisplayFlag annotation

Bug: 113857483
Test: lunch taimen_xr-userdebug; builds; runs
Change-Id: Ide43d77cb3d453586c7df7d4653ed5a23b3e4b21

api/system-current.txt

@@ -474,9 +474,6 @@ package android.app {
     method public android.app.Vr2dDisplayProperties.Builder setEnabled(boolean);
   }
 
-  public static abstract class Vr2dDisplayProperties.Vr2dDisplayFlag implements java.lang.annotation.Annotation {
-  }
-
   public class VrManager {
     method public int getVr2dDisplayId();
     method public boolean isPersistentVrModeEnabled();

core/java/android/app/Vr2dDisplayProperties.java

@@ -35,6 +35,7 @@ public final class Vr2dDisplayProperties implements Parcelable {
 
     public static final int FLAG_VIRTUAL_DISPLAY_ENABLED = 1;
 
+    /** @hide */
     @Retention(RetentionPolicy.SOURCE)
     @IntDef({
         FLAG_VIRTUAL_DISPLAY_ENABLED