code: public static <T> OptionType<T> of(
      final @Nullable T x)
    {
      if (x == null) {
        return None.none();
      }
  
      return Some.some(x);
    }
docs: <p>
  If {@code x == null}, return {@link None}, else return {@link Some}
  containing {@code x}.
  </p>
  
  @param <T> The type of values
  @param x   The value
  
  @return An optional value