code: public static void setQualifiers(String newQualifiers) {
      Configuration configuration;
      DisplayMetrics displayMetrics = new DisplayMetrics();
      if (newQualifiers.startsWith("+")) {
        configuration = new Configuration(Resources.getSystem().getConfiguration());
        displayMetrics.setTo(Resources.getSystem().getDisplayMetrics());
      } else {
        configuration = new Configuration();
      }
      Bootstrap.applyQualifiers(newQualifiers, getApiLevel(), configuration, displayMetrics);
  
      Resources systemResources = Resources.getSystem();
      systemResources.updateConfiguration(configuration, displayMetrics);
  
      if (application != null) {
        application.getResources().updateConfiguration(configuration, displayMetrics);
      }
    }
docs: Overrides the current device configuration.
  
  If `newQualifiers` starts with a plus (`+`), the prior configuration is used as the base
  configuration, with the given changes applied additively. Otherwise, default values are used
  for unspecified properties, as described [here](http://robolectric.org/device-configuration/).
  
  @param newQualifiers the qualifiers to apply