@Override
 public Set<String> getUserSchemas(String user) {
   NgSqlConfig conf = Server.getInstance().getConfig();
   UserConfig uc = conf.getUsers().get(user);
   if (uc != null) {
     return uc.getSchemas();
   } else {
     return null;
   }
 }
 @Override
 public String getPassword(String user) {
   NgSqlConfig conf = Server.getInstance().getConfig();
   if (user != null && user.equals(conf.getSystem().getClusterHeartbeatUser())) {
     return conf.getSystem().getClusterHeartbeatPass();
   } else {
     UserConfig uc = conf.getUsers().get(user);
     if (uc != null) {
       return uc.getPassword();
     } else {
       return null;
     }
   }
 }