Reverse Proxy fails Google Compute Cloud https healthcheck behind TCP load balancer

[absorbb]

Caddy 2.5.2

I try to make Caddy handles all HTTPs in my Google Compute Cloud setup.
So i install caddy behind External TCP load balancer.

Our service relies on client IP. That is why i enable PROXY protocol for load balancer.
and setup your plugin
But once plugin enabled all request must use PROXY protocol that is why i set GCC https health check to use PROXY protocol too,
Problem is that health-check sends PROXY UNKNOWN header. and plugin sets client ip to empty value.
https://cloud.google.com/load-balancing/docs/health-checks#optional-flags-hc-protocol-http

Reverse Proxy fails with error:
preparing request for upstream round-trip: invalid client IP address:
and there is no way health-check will be passed.

I guess replacing IPs with empty values is wrong.
in case of PROXY UNKNOWN header it is better to leave original(proxy) values in requests