private static boolean hasNonInvertedCalls(final RefMethod refMethod) {
   final Boolean alwaysInverted = refMethod.getUserData(ALWAYS_INVERTED);
   if (alwaysInverted == null) return true;
   if (refMethod.isExternalOverride()) return true;
   if (refMethod.isReferenced() && !alwaysInverted.booleanValue()) return true;
   final Collection<RefMethod> superMethods = refMethod.getSuperMethods();
   for (RefMethod superMethod : superMethods) {
     if (hasNonInvertedCalls(superMethod)) return true;
   }
   return false;
 }