docs: public static <E> ImmutableList<E> copyOf(E[] elements) {
      switch (elements.length) {
        case 0:
          return ImmutableList.of();
        case 1:
          return new SingletonImmutableList<E>(elements[0]);
        default:
          return new RegularImmutableList<E>(checkElementsNotNull(elements.clone()));
      }
    }