public PsiClass @NotNull [] getClasses(@Nullable String className, @NotNull PsiPackage psiPackage, @NotNull GlobalSearchScope scope) {
    PsiClass[] allClasses = getClasses(psiPackage, scope);
    if (className == null) return allClasses;
    return filterByName(className, allClasses);
  }
public PsiClass @NotNull [] getClasses(@Nullable String className, @NotNull PsiPackage psiPackage, @NotNull GlobalSearchScope scope)