add http hijack methods (#555)

rest/internal/security/withcoderesponsewriter.go

@@ -1,6 +1,10 @@
 package security
 
-import "net/http"
+import (
+	"bufio"
+	"net"
+	"net/http"
+)
 
 // A WithCodeResponseWriter is a helper to delay sealing a http.ResponseWriter on writing code.
 type WithCodeResponseWriter struct {
@@ -20,6 +24,12 @@ func (w *WithCodeResponseWriter) Header() http.Header {
 	return w.Writer.Header()
 }
 
+// Hijack implements the http.Hijacker interface.
+// This expands the Response to fulfill http.Hijacker if the underlying http.ResponseWriter supports it.
+func (w *WithCodeResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	return w.Writer.(http.Hijacker).Hijack()
+}
+
 // Write writes bytes into w.
 func (w *WithCodeResponseWriter) Write(bytes []byte) (int, error) {
 	return w.Writer.Write(bytes)