code: private OAuthHmacCredential new10aCredential(String userId) {
          ClientParametersAuthentication clientAuthentication = (ClientParametersAuthentication) getClientAuthentication();
          OAuthHmacCredential.Builder builder =
                  new OAuthHmacCredential.Builder(getMethod(), clientAuthentication.getClientId(),
                          clientAuthentication.getClientSecret())
                          .setTransport(getTransport())
                          .setJsonFactory(getJsonFactory())
                          .setTokenServerEncodedUrl(getTokenServerEncodedUrl())
                          .setClientAuthentication(getClientAuthentication())
                          .setRequestInitializer(getRequestInitializer())
                          .setClock(getClock());
          if (getCredentialStore() != null) {
              builder.addRefreshListener(
                      new CredentialStoreRefreshListener(userId, getCredentialStore()));
          }
  
          builder.getRefreshListeners().addAll(getRefreshListeners());
  
          return builder.build();
      }
docs: Returns a new OAuth 1.0a credential instance based on the given user ID.
  
  @param userId user ID or {@code null} if not using a persisted credential
  store