minor change

include/nexuscpp/nxbuffer.h

@@ -496,7 +496,7 @@ public:
     void SetPath(const std::string&, const std::string&);
     void SetWriteNotificationCallback(WriteNotificationCallback& cb) { m_write_notif_cb = cb; }
     void SetWorkingFolder(const std::string&) { }
-    const std::string &GetWorkingFolder() const { return ""; }
+    const std::string &GetWorkingFolder() const { return yat::StringUtil::empty; }
 
   //@}