public static ThreeState existsMutualSubclass(PsiClass class1, PsiClass class2, boolean avoidExpensiveProcessing) {
    if (class1 instanceof PsiTypeParameter) {
      final PsiClass[] superClasses = class1.getSupers();
      ThreeState result = ThreeState.YES;
      for (PsiClass superClass : superClasses) {
        ThreeState state = existsMutualSubclass(superClass, class2, avoidExpensiveProcessing);
        if (state != ThreeState.YES) {
          result = state;
          if (result == ThreeState.NO) {
            return result;
          }
        }
      }
      return result;
    }
    if (class2 instanceof PsiTypeParameter) {
      return existsMutualSubclass(class2, class1, avoidExpensiveProcessing);
    }

    if (CommonClassNames.JAVA_LANG_OBJECT.equals(class1.getQualifiedName())) {
      return ThreeState.YES;
    }
    if (CommonClassNames.JAVA_LANG_OBJECT.equals(class2.getQualifiedName())) {
      return ThreeState.YES;
    }
    if (class1.isInheritor(class2, true) || class2.isInheritor(class1, true) || Objects.equals(class1, class2)) {
      return ThreeState.YES;
    }
    final SearchScope scope = GlobalSearchScope.allScope(class1.getProject());
    String class1Name = class1.getName();
    String class2Name = class2.getName();
    if (class1Name == null || class2Name == null) {
      // One of classes is anonymous? No subclass is possible
      return ThreeState.NO;
    }
    if (class1.hasModifierProperty(PsiModifier.FINAL) || class2.hasModifierProperty(PsiModifier.FINAL)) return ThreeState.NO;
    if (LambdaUtil.isFunctionalClass(class1) || class1Name.length() < class2Name.length() ||
        (isJavaClass(class2) && !isJavaClass(class1))) {
      // Assume that it could be faster to search inheritors from non-functional interface or from class with a longer simple name
      // Also prefer searching inheritors from Java class over other JVM languages as Java is usually faster
      PsiClass tmp = class1;
      class1 = class2;
      class2 = tmp;
    }
    if (DeclarationSearchUtils.isTooExpensiveToSearch(class1, false)) {
      if (!DeclarationSearchUtils.isTooExpensiveToSearch(class2, false)) {
        PsiClass tmp = class1;
        class1 = class2;
        class2 = tmp;
      }
      else if (avoidExpensiveProcessing) {
        // class inheritor search is too expensive on common names
        return ThreeState.UNSURE;
      }
    }
    return doSearch(class1, class2, avoidExpensiveProcessing, scope);
  }
public static ThreeState existsMutualSubclass(PsiClass class1, PsiClass class2, boolean avoidExpensiveProcessing)