Do not overwrite the exsting Twirp headers on the context in the auth middleware (#813)

Author: biglittlebigben

auth.go

@@ -16,10 +16,12 @@ package lksdk
 
 import (
 	"context"
+	"net/http"
 
 	"github.com/twitchtv/twirp"
 
 	"github.com/livekit/protocol/auth"
+
 	"github.com/livekit/server-sdk-go/v2/signalling"
 )
 
@@ -61,5 +63,20 @@ func (b authBase) withAuth(ctx context.Context, opt authOption, options ...authO
 		return nil, err
 	}
 
-	return twirp.WithHTTPRequestHeaders(ctx, signalling.NewHTTPHeaderWithToken(token))
+	h := signalling.NewHTTPHeaderWithToken(token)
+	ctxH, _ := twirp.HTTPRequestHeaders(ctx)
+	if ctxH != nil {
+		ctxH = ctxH.Clone()
+	} else {
+		ctxH = make(http.Header)
+	}
+
+	// merge new header with the ones already present in the context
+	for k, vv := range h {
+		for _, v := range vv {
+			ctxH.Add(k, v)
+		}
+	}
+
+	return twirp.WithHTTPRequestHeaders(ctx, ctxH)
 }