How to unset "gw" attribute when exporting

[Yousong Zhou]

Hi list,

I just tried running BGP over WireGuard link and noticed that routes
were exported to kernel with "via x.x.x.x" attributes.  It's a L3
point-to-point link.  While routing works with or without this
attribute, I am wondering if there is a way to eliminate it.

  10.168.222.0/24 via 169.254.169.1 dev wg1 proto bird metric 32

vs.

  10.168.222.0/24 wg1 scope link

I tried setting "gw = 0.0.0.0" using an export filter, but bird will
complain "Invalid gw address" because 0.0.0.0 is considered as
IADDR_INVALID.

I am relatively new with routing daemons and protocols at the moment,
so any comments are welcome.  Thanks in advance.

Regards,
                yousong