code: public static void assertDispatchQueue(@NonNull DispatchQueue queue) {
  		if (imp != null && (queue == null || !queue.isCurrent())) {
  			imp.assertFailed(StringUtils.format("Expected '%s' queue but was '%s'", queue != null ? queue.getName() : "<missing queue>", Thread.currentThread().getName()));
  		}
  	}
docs: region Threading