code: public Credentials getSafe(){
          Credentials safeCreds = new Credentials(this);
          safeCreds.meta_remove(PASSWORD_KEY);
          safeCreds.meta_remove(AUTH_TOKEN_KEY);
          safeCreds.meta_remove(AUTH_TOKEN_EXPIRE_KEY);
          safeCreds.meta_remove(VALIDATION_KEY);
          safeCreds.meta_remove(PUSH_MESSAGING_KEY);
          safeCreds.meta_remove(RECOVERY_TOKEN_KEY);
          return safeCreds;
      }
docs: New Credentials object which contains no sensitive information, removing
  Password
  auth token
  auth token expiration date
  validation token
  push messaging token
  recovery token
  @return save version of this Credentials object.