… sure proxy is trusted)

With Gin, it's possible to configure the server to read the Client IP from custom headers; examples include `X-Real-Ip` or `CF-Connecting-IP`. This PR makes it possible to set as span attribute the same IP that Gin reads.

Additionally, it makes sure that headers such as "X-Forwarded-For" are used only if Gin is configured to trust the upstream server

PS: Also fixed unit tests, where there were assertions inside handlers, which are executed in separate goroutines

…y-go-contrib into gin-clientip

…y-go-contrib into gin-clientip

Co-authored-by: Damien Mathieu <[email protected]>