private static PsiType genNewListBy(PsiType genericOwner, PsiManager manager) {
   PsiClass list =
       JavaPsiFacade.getInstance(manager.getProject())
           .findClass(JAVA_UTIL_LIST, genericOwner.getResolveScope());
   PsiElementFactory factory = JavaPsiFacade.getElementFactory(manager.getProject());
   if (list == null) return factory.createTypeFromText(JAVA_UTIL_LIST, null);
   return factory.createType(list, PsiUtil.extractIterableTypeParameter(genericOwner, false));
 }
  private static PsiType genNewMapBy(PsiType genericOwner, PsiManager manager) {
    PsiClass map =
        JavaPsiFacade.getInstance(manager.getProject())
            .findClass(JAVA_UTIL_MAP, genericOwner.getResolveScope());
    PsiElementFactory factory = JavaPsiFacade.getElementFactory(manager.getProject());
    if (map == null) return factory.createTypeFromText(JAVA_UTIL_MAP, null);

    final PsiType key = PsiUtil.substituteTypeParameter(genericOwner, JAVA_UTIL_MAP, 0, false);
    final PsiType value = PsiUtil.substituteTypeParameter(genericOwner, JAVA_UTIL_MAP, 1, false);
    return factory.createType(map, key, value);
  }
  @Nullable
  private static PsiClassType createCollection(
      Project project, String collectionName, PsiType... item) {
    PsiElementFactory factory = JavaPsiFacade.getElementFactory(project);
    PsiClass collection =
        JavaPsiFacade.getInstance(project)
            .findClass(collectionName, GlobalSearchScope.allScope(project));
    if (collection == null) return null;

    PsiTypeParameter[] parameters = collection.getTypeParameters();
    if (parameters.length != 1) return null;

    return factory.createType(collection, item);
  }
  @NotNull
  public static PsiType getLeastUpperBound(PsiClass[] classes, PsiManager manager) {
    PsiElementFactory factory = JavaPsiFacade.getElementFactory(manager.getProject());

    if (classes.length == 0) return factory.createTypeByFQClassName(JAVA_LANG_OBJECT);

    PsiType type = factory.createType(classes[0]);

    for (int i = 1; i < classes.length; i++) {
      PsiType t = getLeastUpperBound(type, factory.createType(classes[i]), manager);
      if (t != null) {
        type = t;
      }
    }

    return type;
  }