如何使用spring预定义的类从Okta获取访问令牌？

@Bean
public OAuth2AuthorizedClientManager authorizedClientManager(
        ClientRegistrationRepository clientRegistrationRepository,
        OAuth2AuthorizedClientRepository authorizedClientRepository) {

    OAuth2AuthorizedClientProvider authorizedClientProvider =
            OAuth2AuthorizedClientProviderBuilder.builder()
                    .clientCredentials()
                    .build();

    DefaultOAuth2AuthorizedClientManager authorizedClientManager =
            new DefaultOAuth2AuthorizedClientManager(
                    clientRegistrationRepository, authorizedClientRepository);
    authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);

    return authorizedClientManager;
}

@Configuration
public class OktaOAuth2ClientConfig {

    private final OAuth2AuthorizedClientManager authorizedClientManager;

    public OktaOAuth2ClientConfig(OAuth2AuthorizedClientManager authorizedClientManager) {
        this.authorizedClientManager = authorizedClientManager;
    }

    @Bean
    public ClientRegistrationRepository clientRegistrationRepository() {
        return new InMemoryClientRegistrationRepository(oktaClientRegistration());
    }

    @Bean
    public OAuth2AuthorizedClientRepository authorizedClientRepository() {
        return new HttpSessionOAuth2AuthorizedClientRepository();
    }

    @Bean
    public OAuth2AuthorizedClientService authorizedClientService() {
        return new InMemoryOAuth2AuthorizedClientService(
                clientRegistrationRepository());
    }

    @Bean
    public OAuth2AuthorizedClientProvider authorizedClientProvider() {
        return OAuth2AuthorizedClientProviderBuilder.builder()
                .clientCredentials()
                .build();
    }

    @Bean
    public WebClient webClient(OAuth2AuthorizedClientRepository authorizedClientRepository) {
        ServletOAuth2AuthorizedClientExchangeFilterFunction oauth2 =
                new ServletOAuth2AuthorizedClientExchangeFilterFunction(
                        authorizedClientManager);
        oauth2.setDefaultClientRegistrationId("okta");

        return WebClient.builder()
                .apply(oauth2.oauth2Configuration())
                .build();
    }

    private ClientRegistration oktaClientRegistration() {
        return ClientRegistration.withRegistrationId("okta")
                .clientId("your-client-id")
                .clientSecret("your-client-secret")
                .authorizationGrantType(AuthorizationGrantType.CLIENT_CREDENTIALS)
                .tokenUri("https://your-okta-domain.com/oauth2/default/v1/token")
                .scope("your-scope")
                .build();
    }
}

@Autowired
private OAuth2RestTemplate restTemplate;

public String getAccessTokenFromOkta() {
    OAuth2AccessTokenResponse accessTokenResponse =
            restTemplate.getAccessToken();
    
    // 获取访问令牌
    OAuth2AccessToken accessToken = accessTokenResponse.getAccessToken();
    return accessToken.getTokenValue();
}