JEP 269: Convenience Factory Methods for Collections

[Stephen Colebourne]

On 7 October 2015 at 01:13, Stuart Marks <stuart.marks at oracle.com> wrote:
> My question is, is this enough of a problem that we should allow nulls in
> these collections? I would prefer not to do this, but if there is evidence
> that this would be a mistake, I'd like to hear it.
>
> And if disallowing nulls will cause developers to create things like
> Map<K,Optional<V>>, are we ok with that, and are developers ok with that?

Given what we know now vs when the collections library ws created, I
think it would be a mistake to allow nulls. Developers that
desperately want null in there have other mechanisms to achieve that,
not just Optional. I too would argue against Optional in collections,
at least until value types exist, but thats a social discussion, not
one that can be controlled.

Stephen