I fixed this issue.
I added following lines to the AppDelegate.cpp file.
#ifdef SDKBOX_ENABLED
#include "PluginAdMobJS.hpp"
#include "PluginAdMobJSHelper.h"
#endif
#ifdef SDKBOX_ENABLED
se->addRegisterCallback(register_all_PluginAdMobJS);
se->addRegisterCallback(register_all_PluginAdMobJS_helper);
#endif
this is the solution at Problem with latest SDK box