Local mirror-port and external_ids

[mnenashev]

In case of local mirror-port (SPAN) we have to manually create mapping between interface on the OVS integration bridge to be used as the mirror destination and the name of mirror-port on OVN .
For example:
ovs-vsctl set interface tap_vm1 external-ids:mirror-id=ovn-mirror-01

The question is: it seems logical if the mirroring port at OVS would be created by OVN during:
ovn-nbctl mirror-add mirror-1001 local both ovn-mirror-01 + <ovs_int_name> (tap_vm1)
Yet, it seems like this is not done, why?

The goal is to do all configuration of mirror-port on OVN level and do nothing on OVS one.