improved tracing for debug

internal/net/http/header_utils.go

@@ -2,7 +2,6 @@ package http
 
 import (
 	"net/http"
-	"slices"
 )
 
 func RemoveHop(h http.Header) {
@@ -25,18 +24,30 @@ func CopyHeader(dst, src http.Header) {
 	}
 }
 
-func FilterHeaders(h http.Header, allowed []string) {
-	if allowed == nil {
-		return
+func FilterHeaders(h http.Header, allowed []string) http.Header {
+	if len(allowed) == 0 {
+		return h
 	}
 
-	for i := range allowed {
-		allowed[i] = http.CanonicalHeaderKey(allowed[i])
+	filtered := make(http.Header)
+
+	for i, header := range allowed {
+		values := h.Values(header)
+		if len(values) == 0 {
+			continue
+		}
+		filtered[http.CanonicalHeaderKey(allowed[i])] = append([]string(nil), values...)
 	}
 
-	for key := range h {
-		if !slices.Contains(allowed, key) {
-			h.Del(key)
+	return filtered
+}
+
+func HeaderToMap(h http.Header) map[string]string {
+	result := make(map[string]string)
+	for k, v := range h {
+		if len(v) > 0 {
+			result[k] = v[0] // Take the first value
 		}
 	}
+	return result
 }