how to set smtp-client -> submission_relay_host for IPv4 only?

[PGNet Dev]

ref

   https://dovecot.org/pipermail/dovecot/2020-October/120226.html

> On 10/15/20 10:13 PM, Aki Tuomi wrote:
>> I'm asking how/where to 'tell', via config, Dovecot's smtp-CLIENT, that's making
>> to connection to the submission_relay_host, to use _only_ IPv4.
>
>
> There is currently no (other) way to do this than using /etc/hosts or specifying
> IPv4 address for the relay host.


Is there a bug request opened for this, then ?
Is it planned for implementation ?