разбор json c++ eclips

Добрый день, помогите разобраться, выдает ошибку - error: ISO C++ says that these are ambiguous, even though the worst conversion for the first is better than the worst conversion for the second: [-Werror] String test = (const char*)data[it->key];

версия eclips: Luna Service Release 2 (4.4.2)

 for (JsonObject::iterator it=data.begin(); it!=data.end(); ++it)
 {
     String test = (const char*)data[it->key];
     //tempStr+=String('\"')+it->key+"\",\""+test+"\",";
     //tempStr+=String('\"')+it->key+"\",\""+(const char*)data[it->key]+"\",";
 }