@Nonnull
    @SuppressWarnings("OptionalUsedAsFieldOrParameterType")
    public static <T> NullableOptional<T> fromOptional(@Nonnull Optional<T> value) {
        //noinspection OptionalIsPresent
        return value.isPresent() ? of(value.get()) : empty();
    }
Returns a {@code NullableOptional} describing the specified optional.

@param <T> the class of the value
@param value the possibly-empty value to describe
@return a {@code NullableOptional} with a present value if the specified value
is present, otherwise an empty {@code NullableOptional}
helper/src/main/java/me/lucko/helper/utils/NullableOptional.java