@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);
  }
@Nullable
  private static PsiClassType createCollection(Project project, String collectionName, PsiType... item)