code: public static void changeDisplay(int displayId, String qualifiersStr) {
      DisplayInfo baseDisplayInfo = DisplayManagerGlobal.getInstance().getDisplayInfo(displayId);
      DisplayInfo displayInfo = createDisplayInfo(qualifiersStr, baseDisplayInfo);
      getShadowDisplayManagerGlobal().changeDisplay(displayId, displayInfo);
      shadowMainLooper().idle();
    }
docs: Changes properties of a simulated display. If `qualifiersStr` starts with a plus (`+`) sign,
  the display's previous configuration is modified with the given qualifiers; otherwise defaults
  are applied as described [here](http://robolectric.org/device-configuration/).
  
  <p>Idles the main looper to ensure all listeners are notified.
  
  @param displayId the display id to change
  @param qualifiersStr the {@link Qualifiers} string representing characteristics of the new
  display