code: @Override
    public void saveAuthorizedClient(
        OAuth2AuthorizedClient authorizedClient, Authentication principal) {
      Assert.notNull(authorizedClient, "authorizedClient cannot be null");
      Assert.notNull(principal, "principal cannot be null");
      this.authorizedClients.put(
          this.getIdentifier(authorizedClient.getClientRegistration(), principal.getName()),
          authorizedClient);
    }
docs: Copy of {@link
  InMemoryOAuth2AuthorizedClientService#saveAuthorizedClient(OAuth2AuthorizedClient,
  Authentication)}