docs: public void saveCredentials(@NonNull Credentials credentials) {
          if ((isEmpty(credentials.getAccessToken()) && isEmpty(credentials.getIdToken())) || credentials.getExpiresAt() == null) {
              throw new CredentialsManagerException("Credentials must have a valid date of expiration and a valid access_token or id_token value.");
          }
          storage.store(KEY_ACCESS_TOKEN, credentials.getAccessToken());
          storage.store(KEY_REFRESH_TOKEN, credentials.getRefreshToken());
          storage.store(KEY_ID_TOKEN, credentials.getIdToken());
          storage.store(KEY_TOKEN_TYPE, credentials.getType());
          storage.store(KEY_EXPIRES_AT, credentials.getExpiresAt().getTime());
          storage.store(KEY_SCOPE, credentials.getScope());
      }