docs: public boolean hasValidCredentials() {
          String encryptedEncoded = storage.retrieveString(KEY_CREDENTIALS);
          Long expiresAt = storage.retrieveLong(KEY_EXPIRES_AT);
          Boolean canRefresh = storage.retrieveBoolean(KEY_CAN_REFRESH);
          return !(isEmpty(encryptedEncoded) ||
                  expiresAt == null ||
                  expiresAt <= getCurrentTimeInMillis() && (canRefresh == null || !canRefresh));
      }