@Contract(pure = true)
  @Deprecated
  @ApiStatus.ScheduledForRemoval
  public static @Unmodifiable @NotNull <E> ImmutableList<E> immutableSingletonList(E element) {
    return ImmutableList.singleton(element);
  }
@Contract(pure = true)
  @Deprecated
  @ApiStatus.ScheduledForRemoval
  public static @Unmodifiable @NotNull <E> ImmutableList<E> immutableSingletonList(E element)