How to configure X-Forwarded-Host in kong.conf

Hi,
I am trying to make my UI application publicly available via Kong, but getting issue while authentication, as its redirection URL is different from the downstream URL.

Its forwarding its upstream URL instead of actual URL for authentication.

Can anyone help configuring X-Forwarder-Host ? How I can configure it in my kong.conf

My existing kong.cong

plugins = custom_plugins
trusted_ips = x.x.x.x/x
real_ip_header = X-Forwarded-For
read_ip_recursive = on