Authorization Grant Support

Authorization Code

Please refer to the OAuth 2.0 Authorization Framework for further details on the Authorization Code grant.

Obtaining Authorization

Please refer to the Authorization Request/Response protocol flow for the Authorization Code grant.

Initiating the Authorization Request

The OAuth2AuthorizationRequestRedirectWebFilter uses a ServerOAuth2AuthorizationRequestResolver to resolve an OAuth2AuthorizationRequest and initiate the Authorization Code grant flow by redirecting the end-user’s user-agent to the Authorization Server’s Authorization Endpoint.

The primary role of the ServerOAuth2AuthorizationRequestResolver is to resolve an OAuth2AuthorizationRequest from the provided web request. The default implementation DefaultServerOAuth2AuthorizationRequestResolver matches on the (default) path /oauth2/authorization/{registrationId} extracting the registrationId and using it to build the OAuth2AuthorizationRequest for the associated ClientRegistration.

Given the following Spring Boot properties for an OAuth 2.0 Client registration:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-secret: okta-client-secret
            authorization-grant-type: authorization_code
            redirect-uri: "{baseUrl}/authorized/okta"
            scope: read, write
        provider:
          okta:
            authorization-uri: https://dev-1234.oktapreview.com/oauth2/v1/authorize
            token-uri: https://dev-1234.oktapreview.com/oauth2/v1/token

A request with the base path /oauth2/authorization/okta will initiate the Authorization Request redirect by the OAuth2AuthorizationRequestRedirectWebFilter and ultimately start the Authorization Code grant flow.

The AuthorizationCodeReactiveOAuth2AuthorizedClientProvider is an implementation of ReactiveOAuth2AuthorizedClientProvider for the Authorization Code grant, which also initiates the Authorization Request redirect by the OAuth2AuthorizationRequestRedirectWebFilter.

If the OAuth 2.0 Client is a Public Client, then configure the OAuth 2.0 Client registration as follows:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-authentication-method: none
            authorization-grant-type: authorization_code
            redirect-uri: "{baseUrl}/authorized/okta"
            ...

Public Clients are supported using Proof Key for Code Exchange (PKCE). If the client is running in an untrusted environment (eg. native application or web browser-based application) and therefore incapable of maintaining the confidentiality of it’s credentials, PKCE will automatically be used when the following conditions are true:

  1. client-secret is omitted (or empty)

  2. client-authentication-method is set to "none" (ClientAuthenticationMethod.NONE)

If the OAuth 2.0 Provider supports PKCE for Confidential Clients, you may (optionally) configure it using DefaultServerOAuth2AuthorizationRequestResolver.setAuthorizationRequestCustomizer(OAuth2AuthorizationRequestCustomizers.withPkce()).

The DefaultServerOAuth2AuthorizationRequestResolver also supports URI template variables for the redirect-uri using UriComponentsBuilder.

The following configuration uses all the supported URI template variables:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            ...
            redirect-uri: "{baseScheme}://{baseHost}{basePort}{basePath}/authorized/{registrationId}"
            ...
{baseUrl} resolves to {baseScheme}://{baseHost}{basePort}{basePath}

Configuring the redirect-uri with URI template variables is especially useful when the OAuth 2.0 Client is running behind a Proxy Server. This ensures that the X-Forwarded-* headers are used when expanding the redirect-uri.

Customizing the Authorization Request

One of the primary use cases a ServerOAuth2AuthorizationRequestResolver can realize is the ability to customize the Authorization Request with additional parameters above the standard parameters defined in the OAuth 2.0 Authorization Framework.

For example, OpenID Connect defines additional OAuth 2.0 request parameters for the Authorization Code Flow extending from the standard parameters defined in the OAuth 2.0 Authorization Framework. One of those extended parameters is the prompt parameter.

The prompt parameter is optional. Space delimited, case sensitive list of ASCII string values that specifies whether the Authorization Server prompts the End-User for re-authentication and consent. The defined values are: none, login, consent, and select_account.

The following example shows how to configure the DefaultServerOAuth2AuthorizationRequestResolver with a Consumer<OAuth2AuthorizationRequest.Builder> that customizes the Authorization Request for oauth2Login(), by including the request parameter prompt=consent.

  • Java

  • Kotlin

@Configuration
@EnableWebFluxSecurity
public class OAuth2LoginSecurityConfig {

	@Autowired
	private ReactiveClientRegistrationRepository clientRegistrationRepository;

	@Bean
	public SecurityWebFilterChain securityWebFilterChain(ServerHttpSecurity http) {
		http
			.authorizeExchange(authorize -> authorize
				.anyExchange().authenticated()
			)
			.oauth2Login(oauth2 -> oauth2
				.authorizationRequestResolver(
					authorizationRequestResolver(this.clientRegistrationRepository)
				)
			);
		return http.build();
	}

	private ServerOAuth2AuthorizationRequestResolver authorizationRequestResolver(
			ReactiveClientRegistrationRepository clientRegistrationRepository) {

		DefaultServerOAuth2AuthorizationRequestResolver authorizationRequestResolver =
				new DefaultServerOAuth2AuthorizationRequestResolver(
						clientRegistrationRepository);
		authorizationRequestResolver.setAuthorizationRequestCustomizer(
				authorizationRequestCustomizer());

		return  authorizationRequestResolver;
	}

	private Consumer<OAuth2AuthorizationRequest.Builder> authorizationRequestCustomizer() {
		return customizer -> customizer
					.additionalParameters(params -> params.put("prompt", "consent"));
	}
}
@Configuration
@EnableWebFluxSecurity
class SecurityConfig {

    @Autowired
    private lateinit var customClientRegistrationRepository: ReactiveClientRegistrationRepository

    @Bean
    fun securityFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
        http {
            authorizeExchange {
                authorize(anyExchange, authenticated)
            }
            oauth2Login {
                authorizationRequestResolver = authorizationRequestResolver(customClientRegistrationRepository)
            }
        }

        return http.build()
    }

    private fun authorizationRequestResolver(
            clientRegistrationRepository: ReactiveClientRegistrationRepository): ServerOAuth2AuthorizationRequestResolver {
        val authorizationRequestResolver = DefaultServerOAuth2AuthorizationRequestResolver(
                clientRegistrationRepository)
        authorizationRequestResolver.setAuthorizationRequestCustomizer(
                authorizationRequestCustomizer())
        return authorizationRequestResolver
    }

    private fun authorizationRequestCustomizer(): Consumer<OAuth2AuthorizationRequest.Builder> {
        return Consumer { customizer ->
            customizer
                .additionalParameters { params -> params["prompt"] = "consent" }
        }
    }
}

For the simple use case, where the additional request parameter is always the same for a specific provider, it may be added directly in the authorization-uri property.

For example, if the value for the request parameter prompt is always consent for the provider okta, than simply configure as follows:

spring:
  security:
    oauth2:
      client:
        provider:
          okta:
            authorization-uri: https://dev-1234.oktapreview.com/oauth2/v1/authorize?prompt=consent

The preceding example shows the common use case of adding a custom parameter on top of the standard parameters. Alternatively, if your requirements are more advanced, you can take full control in building the Authorization Request URI by simply overriding the OAuth2AuthorizationRequest.authorizationRequestUri property.

OAuth2AuthorizationRequest.Builder.build() constructs the OAuth2AuthorizationRequest.authorizationRequestUri, which represents the Authorization Request URI including all query parameters using the application/x-www-form-urlencoded format.

The following example shows a variation of authorizationRequestCustomizer() from the preceding example, and instead overrides the OAuth2AuthorizationRequest.authorizationRequestUri property.

  • Java

  • Kotlin

private Consumer<OAuth2AuthorizationRequest.Builder> authorizationRequestCustomizer() {
	return customizer -> customizer
			.authorizationRequestUri(uriBuilder -> uriBuilder
					.queryParam("prompt", "consent").build());
}
private fun authorizationRequestCustomizer(): Consumer<OAuth2AuthorizationRequest.Builder> {
    return Consumer { customizer: OAuth2AuthorizationRequest.Builder ->
        customizer
                .authorizationRequestUri { uriBuilder: UriBuilder ->
                    uriBuilder
                            .queryParam("prompt", "consent").build()
                }
    }
}

Storing the Authorization Request

The ServerAuthorizationRequestRepository is responsible for the persistence of the OAuth2AuthorizationRequest from the time the Authorization Request is initiated to the time the Authorization Response is received (the callback).

The OAuth2AuthorizationRequest is used to correlate and validate the Authorization Response.

The default implementation of ServerAuthorizationRequestRepository is WebSessionOAuth2ServerAuthorizationRequestRepository, which stores the OAuth2AuthorizationRequest in the WebSession.

If you have a custom implementation of ServerAuthorizationRequestRepository, you may configure it as shown in the following example:

ServerAuthorizationRequestRepository Configuration

  • Java

  • Kotlin

@Configuration
@EnableWebFluxSecurity
public class OAuth2ClientSecurityConfig {

	@Bean
	public SecurityWebFilterChain securityWebFilterChain(ServerHttpSecurity http) {
		http
			.oauth2Client(oauth2 -> oauth2
				.authorizationRequestRepository(this.authorizationRequestRepository())
				...
			);
		return http.build();
	}
}
@Configuration
@EnableWebFluxSecurity
class OAuth2ClientSecurityConfig {

    @Bean
    fun securityFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
        http {
            oauth2Client {
                authorizationRequestRepository = authorizationRequestRepository()
            }
        }

        return http.build()
    }
}

Requesting an Access Token

Please refer to the Access Token Request/Response protocol flow for the Authorization Code grant.

The default implementation of ReactiveOAuth2AccessTokenResponseClient for the Authorization Code grant is WebClientReactiveAuthorizationCodeTokenResponseClient, which uses a WebClient for exchanging an authorization code for an access token at the Authorization Server’s Token Endpoint.

The WebClientReactiveAuthorizationCodeTokenResponseClient is quite flexible as it allows you to customize the pre-processing of the Token Request and/or post-handling of the Token Response.

Customizing the Access Token Request

If you need to customize the pre-processing of the Token Request, you can provide WebClientReactiveAuthorizationCodeTokenResponseClient.setParametersConverter() with a custom Converter<OAuth2AuthorizationCodeGrantRequest, MultiValueMap<String, String>>. The default implementation builds a MultiValueMap<String, String> containing only the grant_type parameter of a standard OAuth 2.0 Access Token Request which is used to construct the request. Other parameters required by the Authorization Code grant are added directly to the body of the request by the WebClientReactiveAuthorizationCodeTokenResponseClient. However, providing a custom Converter, would allow you to extend the standard Token Request and add custom parameter(s).

If you prefer to only add additional parameters, you can instead provide WebClientReactiveAuthorizationCodeTokenResponseClient.addParametersConverter() with a custom Converter<OAuth2AuthorizationCodeGrantRequest, MultiValueMap<String, String>> which constructs an aggregate Converter.
The custom Converter must return valid parameters of an OAuth 2.0 Access Token Request that is understood by the intended OAuth 2.0 Provider.

Customizing the Access Token Response

On the other end, if you need to customize the post-handling of the Token Response, you will need to provide WebClientReactiveAuthorizationCodeTokenResponseClient.setBodyExtractor() with a custom configured BodyExtractor<Mono<OAuth2AccessTokenResponse>, ReactiveHttpInputMessage> that is used for converting the OAuth 2.0 Access Token Response to an OAuth2AccessTokenResponse. The default implementation provided by OAuth2BodyExtractors.oauth2AccessTokenResponse() parses the response and handles errors accordingly.

Customizing the WebClient

Alternatively, if your requirements are more advanced, you can take full control of the request/response by simply providing WebClientReactiveAuthorizationCodeTokenResponseClient.setWebClient() with a custom configured WebClient.

Whether you customize WebClientReactiveAuthorizationCodeTokenResponseClient or provide your own implementation of ReactiveOAuth2AccessTokenResponseClient, you’ll need to configure it as shown in the following example:

Access Token Response Configuration

  • Java

  • Kotlin

@Configuration
@EnableWebFluxSecurity
public class OAuth2ClientSecurityConfig {

	@Bean
	public SecurityWebFilterChain securityWebFilterChain(ServerHttpSecurity http) {
		http
			.oauth2Client(oauth2 -> oauth2
				.authenticationManager(this.authorizationCodeAuthenticationManager())
				...
			);
		return http.build();
	}

	private ReactiveAuthenticationManager authorizationCodeAuthenticationManager() {
		WebClientReactiveAuthorizationCodeTokenResponseClient accessTokenResponseClient =
				new WebClientReactiveAuthorizationCodeTokenResponseClient();
		...

		return new OAuth2AuthorizationCodeReactiveAuthenticationManager(accessTokenResponseClient);
	}
}
@Configuration
@EnableWebFluxSecurity
class OAuth2ClientSecurityConfig {

    @Bean
    fun securityFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
        http {
            oauth2Client {
                authenticationManager = authorizationCodeAuthenticationManager()
            }
        }

        return http.build()
    }

    private fun authorizationCodeAuthenticationManager(): ReactiveAuthenticationManager {
        val accessTokenResponseClient = WebClientReactiveAuthorizationCodeTokenResponseClient()
        ...

        return OAuth2AuthorizationCodeReactiveAuthenticationManager(accessTokenResponseClient)
    }
}

Refresh Token

Please refer to the OAuth 2.0 Authorization Framework for further details on the Refresh Token.

Refreshing an Access Token

Please refer to the Access Token Request/Response protocol flow for the Refresh Token grant.

The default implementation of ReactiveOAuth2AccessTokenResponseClient for the Refresh Token grant is WebClientReactiveRefreshTokenTokenResponseClient, which uses a WebClient when refreshing an access token at the Authorization Server’s Token Endpoint.

The WebClientReactiveRefreshTokenTokenResponseClient is quite flexible as it allows you to customize the pre-processing of the Token Request and/or post-handling of the Token Response.

Customizing the Access Token Request

If you need to customize the pre-processing of the Token Request, you can provide WebClientReactiveRefreshTokenTokenResponseClient.setParametersConverter() with a custom Converter<OAuth2RefreshTokenGrantRequest, MultiValueMap<String, String>>. The default implementation builds a MultiValueMap<String, String> containing only the grant_type parameter of a standard OAuth 2.0 Access Token Request which is used to construct the request. Other parameters required by the Refresh Token grant are added directly to the body of the request by the WebClientReactiveRefreshTokenTokenResponseClient. However, providing a custom Converter, would allow you to extend the standard Token Request and add custom parameter(s).

If you prefer to only add additional parameters, you can instead provide WebClientReactiveRefreshTokenTokenResponseClient.addParametersConverter() with a custom Converter<OAuth2RefreshTokenGrantRequest, MultiValueMap<String, String>> which constructs an aggregate Converter.
The custom Converter must return valid parameters of an OAuth 2.0 Access Token Request that is understood by the intended OAuth 2.0 Provider.

Customizing the Access Token Response

On the other end, if you need to customize the post-handling of the Token Response, you will need to provide WebClientReactiveRefreshTokenTokenResponseClient.setBodyExtractor() with a custom configured BodyExtractor<Mono<OAuth2AccessTokenResponse>, ReactiveHttpInputMessage> that is used for converting the OAuth 2.0 Access Token Response to an OAuth2AccessTokenResponse. The default implementation provided by OAuth2BodyExtractors.oauth2AccessTokenResponse() parses the response and handles errors accordingly.

Customizing the WebClient

Alternatively, if your requirements are more advanced, you can take full control of the request/response by simply providing WebClientReactiveRefreshTokenTokenResponseClient.setWebClient() with a custom configured WebClient.

Whether you customize WebClientReactiveRefreshTokenTokenResponseClient or provide your own implementation of ReactiveOAuth2AccessTokenResponseClient, you’ll need to configure it as shown in the following example:

Access Token Response Configuration

  • Java

  • Kotlin

// Customize
ReactiveOAuth2AccessTokenResponseClient<OAuth2RefreshTokenGrantRequest> refreshTokenTokenResponseClient = ...

ReactiveOAuth2AuthorizedClientProvider authorizedClientProvider =
		ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
				.authorizationCode()
				.refreshToken(configurer -> configurer.accessTokenResponseClient(refreshTokenTokenResponseClient))
				.build();

...

authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);
// Customize
val refreshTokenTokenResponseClient: ReactiveOAuth2AccessTokenResponseClient<OAuth2RefreshTokenGrantRequest> = ...

val authorizedClientProvider: ReactiveOAuth2AuthorizedClientProvider = ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
        .authorizationCode()
        .refreshToken { it.accessTokenResponseClient(refreshTokenTokenResponseClient) }
        .build()

...

authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider)
ReactiveOAuth2AuthorizedClientProviderBuilder.builder().refreshToken() configures a RefreshTokenReactiveOAuth2AuthorizedClientProvider, which is an implementation of a ReactiveOAuth2AuthorizedClientProvider for the Refresh Token grant.

The OAuth2RefreshToken may optionally be returned in the Access Token Response for the authorization_code and password grant types. If the OAuth2AuthorizedClient.getRefreshToken() is available and the OAuth2AuthorizedClient.getAccessToken() is expired, it will automatically be refreshed by the RefreshTokenReactiveOAuth2AuthorizedClientProvider.

Client Credentials

Please refer to the OAuth 2.0 Authorization Framework for further details on the Client Credentials grant.

Requesting an Access Token

Please refer to the Access Token Request/Response protocol flow for the Client Credentials grant.

The default implementation of ReactiveOAuth2AccessTokenResponseClient for the Client Credentials grant is WebClientReactiveClientCredentialsTokenResponseClient, which uses a WebClient when requesting an access token at the Authorization Server’s Token Endpoint.

The WebClientReactiveClientCredentialsTokenResponseClient is quite flexible as it allows you to customize the pre-processing of the Token Request and/or post-handling of the Token Response.

Customizing the Access Token Request

If you need to customize the pre-processing of the Token Request, you can provide WebClientReactiveClientCredentialsTokenResponseClient.setParametersConverter() with a custom Converter<OAuth2ClientCredentialsGrantRequest, MultiValueMap<String, String>>. The default implementation builds a MultiValueMap<String, String> containing only the grant_type parameter of a standard OAuth 2.0 Access Token Request which is used to construct the request. Other parameters required by the Client Credentials grant are added directly to the body of the request by the WebClientReactiveClientCredentialsTokenResponseClient. However, providing a custom Converter, would allow you to extend the standard Token Request and add custom parameter(s).

If you prefer to only add additional parameters, you can instead provide WebClientReactiveClientCredentialsTokenResponseClient.addParametersConverter() with a custom Converter<OAuth2ClientCredentialsGrantRequest, MultiValueMap<String, String>> which constructs an aggregate Converter.
The custom Converter must return valid parameters of an OAuth 2.0 Access Token Request that is understood by the intended OAuth 2.0 Provider.

Customizing the Access Token Response

On the other end, if you need to customize the post-handling of the Token Response, you will need to provide WebClientReactiveClientCredentialsTokenResponseClient.setBodyExtractor() with a custom configured BodyExtractor<Mono<OAuth2AccessTokenResponse>, ReactiveHttpInputMessage> that is used for converting the OAuth 2.0 Access Token Response to an OAuth2AccessTokenResponse. The default implementation provided by OAuth2BodyExtractors.oauth2AccessTokenResponse() parses the response and handles errors accordingly.

Customizing the WebClient

Alternatively, if your requirements are more advanced, you can take full control of the request/response by simply providing WebClientReactiveClientCredentialsTokenResponseClient.setWebClient() with a custom configured WebClient.

Whether you customize WebClientReactiveClientCredentialsTokenResponseClient or provide your own implementation of ReactiveOAuth2AccessTokenResponseClient, you’ll need to configure it as shown in the following example:

  • Java

  • Kotlin

// Customize
ReactiveOAuth2AccessTokenResponseClient<OAuth2ClientCredentialsGrantRequest> clientCredentialsTokenResponseClient = ...

ReactiveOAuth2AuthorizedClientProvider authorizedClientProvider =
		ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
				.clientCredentials(configurer -> configurer.accessTokenResponseClient(clientCredentialsTokenResponseClient))
				.build();

...

authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);
// Customize
val clientCredentialsTokenResponseClient: ReactiveOAuth2AccessTokenResponseClient<OAuth2ClientCredentialsGrantRequest> = ...

val authorizedClientProvider: ReactiveOAuth2AuthorizedClientProvider = ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
        .clientCredentials { it.accessTokenResponseClient(clientCredentialsTokenResponseClient) }
        .build()

...

authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider)
ReactiveOAuth2AuthorizedClientProviderBuilder.builder().clientCredentials() configures a ClientCredentialsReactiveOAuth2AuthorizedClientProvider, which is an implementation of a ReactiveOAuth2AuthorizedClientProvider for the Client Credentials grant.

Using the Access Token

Given the following Spring Boot properties for an OAuth 2.0 Client registration:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-secret: okta-client-secret
            authorization-grant-type: client_credentials
            scope: read, write
        provider:
          okta:
            token-uri: https://dev-1234.oktapreview.com/oauth2/v1/token

…​and the ReactiveOAuth2AuthorizedClientManager @Bean:

  • Java

  • Kotlin

@Bean
public ReactiveOAuth2AuthorizedClientManager authorizedClientManager(
		ReactiveClientRegistrationRepository clientRegistrationRepository,
		ServerOAuth2AuthorizedClientRepository authorizedClientRepository) {

	ReactiveOAuth2AuthorizedClientProvider authorizedClientProvider =
			ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
					.clientCredentials()
					.build();

	DefaultReactiveOAuth2AuthorizedClientManager authorizedClientManager =
			new DefaultReactiveOAuth2AuthorizedClientManager(
					clientRegistrationRepository, authorizedClientRepository);
	authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);

	return authorizedClientManager;
}
@Bean
fun authorizedClientManager(
        clientRegistrationRepository: ReactiveClientRegistrationRepository,
        authorizedClientRepository: ServerOAuth2AuthorizedClientRepository): ReactiveOAuth2AuthorizedClientManager {
    val authorizedClientProvider: ReactiveOAuth2AuthorizedClientProvider = ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
            .clientCredentials()
            .build()
    val authorizedClientManager = DefaultReactiveOAuth2AuthorizedClientManager(
            clientRegistrationRepository, authorizedClientRepository)
    authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider)
    return authorizedClientManager
}

You may obtain the OAuth2AccessToken as follows:

  • Java

  • Kotlin

@Controller
public class OAuth2ClientController {

	@Autowired
	private ReactiveOAuth2AuthorizedClientManager authorizedClientManager;

	@GetMapping("/")
	public Mono<String> index(Authentication authentication, ServerWebExchange exchange) {
		OAuth2AuthorizeRequest authorizeRequest = OAuth2AuthorizeRequest.withClientRegistrationId("okta")
				.principal(authentication)
				.attribute(ServerWebExchange.class.getName(), exchange)
				.build();

		return this.authorizedClientManager.authorize(authorizeRequest)
				.map(OAuth2AuthorizedClient::getAccessToken)
				...
				.thenReturn("index");
	}
}
class OAuth2ClientController {

    @Autowired
    private lateinit var authorizedClientManager: ReactiveOAuth2AuthorizedClientManager

    @GetMapping("/")
    fun index(authentication: Authentication, exchange: ServerWebExchange): Mono<String> {
        val authorizeRequest = OAuth2AuthorizeRequest.withClientRegistrationId("okta")
                .principal(authentication)
                .attribute(ServerWebExchange::class.java.name, exchange)
                .build()

        return authorizedClientManager.authorize(authorizeRequest)
                .map { it.accessToken }
                ...
                .thenReturn("index")
    }
}
ServerWebExchange is an OPTIONAL attribute. If not provided, it will be obtained from the Reactor’s Context via the key ServerWebExchange.class.

Resource Owner Password Credentials

Please refer to the OAuth 2.0 Authorization Framework for further details on the Resource Owner Password Credentials grant.

Requesting an Access Token

Please refer to the Access Token Request/Response protocol flow for the Resource Owner Password Credentials grant.

The default implementation of ReactiveOAuth2AccessTokenResponseClient for the Resource Owner Password Credentials grant is WebClientReactivePasswordTokenResponseClient, which uses a WebClient when requesting an access token at the Authorization Server’s Token Endpoint.

The WebClientReactivePasswordTokenResponseClient is quite flexible as it allows you to customize the pre-processing of the Token Request and/or post-handling of the Token Response.

Customizing the Access Token Request

If you need to customize the pre-processing of the Token Request, you can provide WebClientReactivePasswordTokenResponseClient.setParametersConverter() with a custom Converter<OAuth2PasswordGrantRequest, MultiValueMap<String, String>>. The default implementation builds a MultiValueMap<String, String> containing only the grant_type parameter of a standard OAuth 2.0 Access Token Request which is used to construct the request. Other parameters required by the Resource Owner Password Credentials grant are added directly to the body of the request by the WebClientReactivePasswordTokenResponseClient. However, providing a custom Converter, would allow you to extend the standard Token Request and add custom parameter(s).

If you prefer to only add additional parameters, you can instead provide WebClientReactivePasswordTokenResponseClient.addParametersConverter() with a custom Converter<OAuth2PasswordGrantRequest, MultiValueMap<String, String>> which constructs an aggregate Converter.
The custom Converter must return valid parameters of an OAuth 2.0 Access Token Request that is understood by the intended OAuth 2.0 Provider.

Customizing the Access Token Response

On the other end, if you need to customize the post-handling of the Token Response, you will need to provide WebClientReactivePasswordTokenResponseClient.setBodyExtractor() with a custom configured BodyExtractor<Mono<OAuth2AccessTokenResponse>, ReactiveHttpInputMessage> that is used for converting the OAuth 2.0 Access Token Response to an OAuth2AccessTokenResponse. The default implementation provided by OAuth2BodyExtractors.oauth2AccessTokenResponse() parses the response and handles errors accordingly.

Customizing the WebClient

Alternatively, if your requirements are more advanced, you can take full control of the request/response by simply providing WebClientReactivePasswordTokenResponseClient.setWebClient() with a custom configured WebClient.

Whether you customize WebClientReactivePasswordTokenResponseClient or provide your own implementation of ReactiveOAuth2AccessTokenResponseClient, you’ll need to configure it as shown in the following example:

  • Java

  • Kotlin

// Customize
ReactiveOAuth2AccessTokenResponseClient<OAuth2PasswordGrantRequest> passwordTokenResponseClient = ...

ReactiveOAuth2AuthorizedClientProvider authorizedClientProvider =
		ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
				.password(configurer -> configurer.accessTokenResponseClient(passwordTokenResponseClient))
				.refreshToken()
				.build();

...

authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);
val passwordTokenResponseClient: ReactiveOAuth2AccessTokenResponseClient<OAuth2PasswordGrantRequest> = ...

val authorizedClientProvider = ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
        .password { it.accessTokenResponseClient(passwordTokenResponseClient) }
        .refreshToken()
        .build()

...

authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider)
ReactiveOAuth2AuthorizedClientProviderBuilder.builder().password() configures a PasswordReactiveOAuth2AuthorizedClientProvider, which is an implementation of a ReactiveOAuth2AuthorizedClientProvider for the Resource Owner Password Credentials grant.

Using the Access Token

Given the following Spring Boot properties for an OAuth 2.0 Client registration:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-secret: okta-client-secret
            authorization-grant-type: password
            scope: read, write
        provider:
          okta:
            token-uri: https://dev-1234.oktapreview.com/oauth2/v1/token

…​and the ReactiveOAuth2AuthorizedClientManager @Bean:

  • Java

  • Kotlin

@Bean
public ReactiveOAuth2AuthorizedClientManager authorizedClientManager(
		ReactiveClientRegistrationRepository clientRegistrationRepository,
		ServerOAuth2AuthorizedClientRepository authorizedClientRepository) {

	ReactiveOAuth2AuthorizedClientProvider authorizedClientProvider =
			ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
					.password()
					.refreshToken()
					.build();

	DefaultReactiveOAuth2AuthorizedClientManager authorizedClientManager =
			new DefaultReactiveOAuth2AuthorizedClientManager(
					clientRegistrationRepository, authorizedClientRepository);
	authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);

	// Assuming the `username` and `password` are supplied as `ServerHttpRequest` parameters,
	// map the `ServerHttpRequest` parameters to `OAuth2AuthorizationContext.getAttributes()`
	authorizedClientManager.setContextAttributesMapper(contextAttributesMapper());

	return authorizedClientManager;
}

private Function<OAuth2AuthorizeRequest, Mono<Map<String, Object>>> contextAttributesMapper() {
	return authorizeRequest -> {
		Map<String, Object> contextAttributes = Collections.emptyMap();
		ServerWebExchange exchange = authorizeRequest.getAttribute(ServerWebExchange.class.getName());
		ServerHttpRequest request = exchange.getRequest();
		String username = request.getQueryParams().getFirst(OAuth2ParameterNames.USERNAME);
		String password = request.getQueryParams().getFirst(OAuth2ParameterNames.PASSWORD);
		if (StringUtils.hasText(username) && StringUtils.hasText(password)) {
			contextAttributes = new HashMap<>();

			// `PasswordReactiveOAuth2AuthorizedClientProvider` requires both attributes
			contextAttributes.put(OAuth2AuthorizationContext.USERNAME_ATTRIBUTE_NAME, username);
			contextAttributes.put(OAuth2AuthorizationContext.PASSWORD_ATTRIBUTE_NAME, password);
		}
		return Mono.just(contextAttributes);
	};
}
@Bean
fun authorizedClientManager(
        clientRegistrationRepository: ReactiveClientRegistrationRepository,
        authorizedClientRepository: ServerOAuth2AuthorizedClientRepository): ReactiveOAuth2AuthorizedClientManager {
    val authorizedClientProvider: ReactiveOAuth2AuthorizedClientProvider = ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
            .password()
            .refreshToken()
            .build()
    val authorizedClientManager = DefaultReactiveOAuth2AuthorizedClientManager(
            clientRegistrationRepository, authorizedClientRepository)
    authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider)

    // Assuming the `username` and `password` are supplied as `ServerHttpRequest` parameters,
    // map the `ServerHttpRequest` parameters to `OAuth2AuthorizationContext.getAttributes()`
    authorizedClientManager.setContextAttributesMapper(contextAttributesMapper())
    return authorizedClientManager
}

private fun contextAttributesMapper(): Function<OAuth2AuthorizeRequest, Mono<MutableMap<String, Any>>> {
    return Function { authorizeRequest ->
        var contextAttributes: MutableMap<String, Any> = mutableMapOf()
        val exchange: ServerWebExchange = authorizeRequest.getAttribute(ServerWebExchange::class.java.name)!!
        val request: ServerHttpRequest = exchange.request
        val username: String? = request.queryParams.getFirst(OAuth2ParameterNames.USERNAME)
        val password: String? = request.queryParams.getFirst(OAuth2ParameterNames.PASSWORD)
        if (StringUtils.hasText(username) && StringUtils.hasText(password)) {
            contextAttributes = hashMapOf()

            // `PasswordReactiveOAuth2AuthorizedClientProvider` requires both attributes
            contextAttributes[OAuth2AuthorizationContext.USERNAME_ATTRIBUTE_NAME] = username!!
            contextAttributes[OAuth2AuthorizationContext.PASSWORD_ATTRIBUTE_NAME] = password!!
        }
        Mono.just(contextAttributes)
    }
}

You may obtain the OAuth2AccessToken as follows:

  • Java

  • Kotlin

@Controller
public class OAuth2ClientController {

	@Autowired
	private ReactiveOAuth2AuthorizedClientManager authorizedClientManager;

	@GetMapping("/")
	public Mono<String> index(Authentication authentication, ServerWebExchange exchange) {
		OAuth2AuthorizeRequest authorizeRequest = OAuth2AuthorizeRequest.withClientRegistrationId("okta")
				.principal(authentication)
				.attribute(ServerWebExchange.class.getName(), exchange)
				.build();

		return this.authorizedClientManager.authorize(authorizeRequest)
				.map(OAuth2AuthorizedClient::getAccessToken)
				...
				.thenReturn("index");
	}
}
@Controller
class OAuth2ClientController {
    @Autowired
    private lateinit var authorizedClientManager: ReactiveOAuth2AuthorizedClientManager

    @GetMapping("/")
    fun index(authentication: Authentication, exchange: ServerWebExchange): Mono<String> {
        val authorizeRequest = OAuth2AuthorizeRequest.withClientRegistrationId("okta")
                .principal(authentication)
                .attribute(ServerWebExchange::class.java.name, exchange)
                .build()

        return authorizedClientManager.authorize(authorizeRequest)
                .map { it.accessToken }
                ...
                .thenReturn("index")
    }
}
ServerWebExchange is an OPTIONAL attribute. If not provided, it will be obtained from the Reactor’s Context via the key ServerWebExchange.class.

JWT Bearer

Please refer to JSON Web Token (JWT) Profile for OAuth 2.0 Client Authentication and Authorization Grants for further details on the JWT Bearer grant.

Requesting an Access Token

Please refer to the Access Token Request/Response protocol flow for the JWT Bearer grant.

The default implementation of ReactiveOAuth2AccessTokenResponseClient for the JWT Bearer grant is WebClientReactiveJwtBearerTokenResponseClient, which uses a WebClient when requesting an access token at the Authorization Server’s Token Endpoint.

The WebClientReactiveJwtBearerTokenResponseClient is quite flexible as it allows you to customize the pre-processing of the Token Request and/or post-handling of the Token Response.

Customizing the Access Token Request

If you need to customize the pre-processing of the Token Request, you can provide WebClientReactiveJwtBearerTokenResponseClient.setParametersConverter() with a custom Converter<JwtBearerGrantRequest, MultiValueMap<String, String>>. The default implementation builds a MultiValueMap<String, String> containing only the grant_type parameter of a standard OAuth 2.0 Access Token Request which is used to construct the request. Other parameters required by the JWT Bearer grant are added directly to the body of the request by the WebClientReactiveJwtBearerTokenResponseClient. However, providing a custom Converter, would allow you to extend the standard Token Request and add custom parameter(s).

If you prefer to only add additional parameters, you can instead provide WebClientReactiveJwtBearerTokenResponseClient.addParametersConverter() with a custom Converter<JwtBearerGrantRequest, MultiValueMap<String, String>> which constructs an aggregate Converter.
The custom Converter must return valid parameters of an OAuth 2.0 Access Token Request that is understood by the intended OAuth 2.0 Provider.

Customizing the Access Token Response

On the other end, if you need to customize the post-handling of the Token Response, you will need to provide WebClientReactiveJwtBearerTokenResponseClient.setBodyExtractor() with a custom configured BodyExtractor<Mono<OAuth2AccessTokenResponse>, ReactiveHttpInputMessage> that is used for converting the OAuth 2.0 Access Token Response to an OAuth2AccessTokenResponse. The default implementation provided by OAuth2BodyExtractors.oauth2AccessTokenResponse() parses the response and handles errors accordingly.

Customizing the WebClient

Alternatively, if your requirements are more advanced, you can take full control of the request/response by simply providing WebClientReactiveJwtBearerTokenResponseClient.setWebClient() with a custom configured WebClient.

Whether you customize WebClientReactiveJwtBearerTokenResponseClient or provide your own implementation of ReactiveOAuth2AccessTokenResponseClient, you’ll need to configure it as shown in the following example:

  • Java

  • Kotlin

// Customize
ReactiveOAuth2AccessTokenResponseClient<JwtBearerGrantRequest> jwtBearerTokenResponseClient = ...

JwtBearerReactiveOAuth2AuthorizedClientProvider jwtBearerAuthorizedClientProvider = new JwtBearerReactiveOAuth2AuthorizedClientProvider();
jwtBearerAuthorizedClientProvider.setAccessTokenResponseClient(jwtBearerTokenResponseClient);

ReactiveOAuth2AuthorizedClientProvider authorizedClientProvider =
		ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
				.provider(jwtBearerAuthorizedClientProvider)
				.build();

...

authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);
// Customize
val jwtBearerTokenResponseClient: ReactiveOAuth2AccessTokenResponseClient<JwtBearerGrantRequest> = ...

val jwtBearerAuthorizedClientProvider = JwtBearerReactiveOAuth2AuthorizedClientProvider()
jwtBearerAuthorizedClientProvider.setAccessTokenResponseClient(jwtBearerTokenResponseClient)

val authorizedClientProvider = ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
        .provider(jwtBearerAuthorizedClientProvider)
        .build()

...

authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider)

Using the Access Token

Given the following Spring Boot properties for an OAuth 2.0 Client registration:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-secret: okta-client-secret
            authorization-grant-type: urn:ietf:params:oauth:grant-type:jwt-bearer
            scope: read
        provider:
          okta:
            token-uri: https://dev-1234.oktapreview.com/oauth2/v1/token

…​and the OAuth2AuthorizedClientManager @Bean:

  • Java

  • Kotlin

@Bean
public ReactiveOAuth2AuthorizedClientManager authorizedClientManager(
		ReactiveClientRegistrationRepository clientRegistrationRepository,
		ServerOAuth2AuthorizedClientRepository authorizedClientRepository) {

	JwtBearerReactiveOAuth2AuthorizedClientProvider jwtBearerAuthorizedClientProvider =
			new JwtBearerReactiveOAuth2AuthorizedClientProvider();

	ReactiveOAuth2AuthorizedClientProvider authorizedClientProvider =
			ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
					.provider(jwtBearerAuthorizedClientProvider)
					.build();

	DefaultReactiveOAuth2AuthorizedClientManager authorizedClientManager =
			new DefaultReactiveOAuth2AuthorizedClientManager(
					clientRegistrationRepository, authorizedClientRepository);
	authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);

	return authorizedClientManager;
}
@Bean
fun authorizedClientManager(
        clientRegistrationRepository: ReactiveClientRegistrationRepository,
        authorizedClientRepository: ServerOAuth2AuthorizedClientRepository): ReactiveOAuth2AuthorizedClientManager {
    val jwtBearerAuthorizedClientProvider = JwtBearerReactiveOAuth2AuthorizedClientProvider()
    val authorizedClientProvider = ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
            .provider(jwtBearerAuthorizedClientProvider)
            .build()
    val authorizedClientManager = DefaultReactiveOAuth2AuthorizedClientManager(
            clientRegistrationRepository, authorizedClientRepository)
    authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider)
    return authorizedClientManager
}

You may obtain the OAuth2AccessToken as follows:

  • Java

  • Kotlin

@RestController
public class OAuth2ResourceServerController {

	@Autowired
	private ReactiveOAuth2AuthorizedClientManager authorizedClientManager;

	@GetMapping("/resource")
	public Mono<String> resource(JwtAuthenticationToken jwtAuthentication, ServerWebExchange exchange) {
		OAuth2AuthorizeRequest authorizeRequest = OAuth2AuthorizeRequest.withClientRegistrationId("okta")
				.principal(jwtAuthentication)
				.build();

		return this.authorizedClientManager.authorize(authorizeRequest)
				.map(OAuth2AuthorizedClient::getAccessToken)
				...
	}
}
class OAuth2ResourceServerController {

    @Autowired
    private lateinit var authorizedClientManager: ReactiveOAuth2AuthorizedClientManager

    @GetMapping("/resource")
    fun resource(jwtAuthentication: JwtAuthenticationToken, exchange: ServerWebExchange): Mono<String> {
        val authorizeRequest = OAuth2AuthorizeRequest.withClientRegistrationId("okta")
                .principal(jwtAuthentication)
                .build()
        return authorizedClientManager.authorize(authorizeRequest)
                .map { it.accessToken }
                ...
    }
}
JwtBearerReactiveOAuth2AuthorizedClientProvider resolves the Jwt assertion via OAuth2AuthorizationContext.getPrincipal().getPrincipal() by default, hence the use of JwtAuthenticationToken in the preceding example.
If you need to resolve the Jwt assertion from a different source, you can provide JwtBearerReactiveOAuth2AuthorizedClientProvider.setJwtAssertionResolver() with a custom Function<OAuth2AuthorizationContext, Mono<Jwt>>.

Token Exchange

Please refer to OAuth 2.0 Token Exchange for further details on the Token Exchange grant.

Requesting an Access Token

Please refer to the Token Exchange Request and Response protocol flow for the Token Exchange grant.

The default implementation of ReactiveOAuth2AccessTokenResponseClient for the Token Exchange grant is WebClientReactiveTokenExchangeTokenResponseClient, which uses a WebClient when requesting an access token at the Authorization Server’s Token Endpoint.

The WebClientReactiveTokenExchangeTokenResponseClient is quite flexible as it allows you to customize the pre-processing of the Token Request and/or post-handling of the Token Response.

Customizing the Access Token Request

If you need to customize the pre-processing of the Token Request, you can provide WebClientReactiveTokenExchangeTokenResponseClient.setParametersConverter() with a custom Converter<TokenExchangeGrantRequest, MultiValueMap<String, String>>. The default implementation builds a MultiValueMap<String, String> containing only the grant_type parameter of a standard OAuth 2.0 Access Token Request which is used to construct the request. Other parameters required by the Token Exchange grant are added directly to the body of the request by the WebClientReactiveTokenExchangeTokenResponseClient. However, providing a custom Converter, would allow you to extend the standard Token Request and add custom parameter(s).

If you prefer to only add additional parameters, you can instead provide WebClientReactiveTokenExchangeTokenResponseClient.addParametersConverter() with a custom Converter<TokenExchangeGrantRequest, MultiValueMap<String, String>> which constructs an aggregate Converter.
The custom Converter must return valid parameters of an OAuth 2.0 Access Token Request that is understood by the intended OAuth 2.0 Provider.

Customizing the Access Token Response

On the other end, if you need to customize the post-handling of the Token Response, you will need to provide WebClientReactiveTokenExchangeTokenResponseClient.setBodyExtractor() with a custom configured BodyExtractor<Mono<OAuth2AccessTokenResponse>, ReactiveHttpInputMessage> that is used for converting the OAuth 2.0 Access Token Response to an OAuth2AccessTokenResponse. The default implementation provided by OAuth2BodyExtractors.oauth2AccessTokenResponse() parses the response and handles errors accordingly.

Customizing the WebClient

Alternatively, if your requirements are more advanced, you can take full control of the request/response by simply providing WebClientReactiveTokenExchangeTokenResponseClient.setWebClient() with a custom configured WebClient.

Whether you customize WebClientReactiveTokenExchangeTokenResponseClient or provide your own implementation of ReactiveOAuth2AccessTokenResponseClient, you’ll need to configure it as shown in the following example:

  • Java

  • Kotlin

// Customize
ReactiveOAuth2AccessTokenResponseClient<TokenExchangeGrantRequest> tokenExchangeTokenResponseClient = ...

TokenExchangeReactiveOAuth2AuthorizedClientProvider tokenExchangeAuthorizedClientProvider = new TokenExchangeReactiveOAuth2AuthorizedClientProvider();
tokenExchangeAuthorizedClientProvider.setAccessTokenResponseClient(tokenExchangeTokenResponseClient);

ReactiveOAuth2AuthorizedClientProvider authorizedClientProvider =
		ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
				.provider(tokenExchangeAuthorizedClientProvider)
				.build();

...

authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);
// Customize
val tokenExchangeTokenResponseClient: ReactiveOAuth2AccessTokenResponseClient<TokenExchangeGrantRequest> = ...

val tokenExchangeAuthorizedClientProvider = TokenExchangeReactiveOAuth2AuthorizedClientProvider()
tokenExchangeAuthorizedClientProvider.setAccessTokenResponseClient(tokenExchangeTokenResponseClient)

val authorizedClientProvider = ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
        .provider(tokenExchangeAuthorizedClientProvider)
        .build()

...

authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider)

Using the Access Token

Given the following Spring Boot properties for an OAuth 2.0 Client registration:

spring:
  security:
    oauth2:
      client:
        registration:
          okta:
            client-id: okta-client-id
            client-secret: okta-client-secret
            authorization-grant-type: urn:ietf:params:oauth:grant-type:token-exchange
            scope: read
        provider:
          okta:
            token-uri: https://dev-1234.oktapreview.com/oauth2/v1/token

…​and the OAuth2AuthorizedClientManager @Bean:

  • Java

  • Kotlin

@Bean
public ReactiveOAuth2AuthorizedClientManager authorizedClientManager(
		ReactiveClientRegistrationRepository clientRegistrationRepository,
		ServerOAuth2AuthorizedClientRepository authorizedClientRepository) {

	TokenExchangeReactiveOAuth2AuthorizedClientProvider tokenExchangeAuthorizedClientProvider =
			new TokenExchangeReactiveOAuth2AuthorizedClientProvider();

	ReactiveOAuth2AuthorizedClientProvider authorizedClientProvider =
			ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
					.provider(tokenExchangeAuthorizedClientProvider)
					.build();

	DefaultReactiveOAuth2AuthorizedClientManager authorizedClientManager =
			new DefaultReactiveOAuth2AuthorizedClientManager(
					clientRegistrationRepository, authorizedClientRepository);
	authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider);

	return authorizedClientManager;
}
@Bean
fun authorizedClientManager(
        clientRegistrationRepository: ReactiveClientRegistrationRepository,
        authorizedClientRepository: ServerOAuth2AuthorizedClientRepository): ReactiveOAuth2AuthorizedClientManager {
    val tokenExchangeAuthorizedClientProvider = TokenExchangeReactiveOAuth2AuthorizedClientProvider()
    val authorizedClientProvider = ReactiveOAuth2AuthorizedClientProviderBuilder.builder()
            .provider(tokenExchangeAuthorizedClientProvider)
            .build()
    val authorizedClientManager = DefaultReactiveOAuth2AuthorizedClientManager(
            clientRegistrationRepository, authorizedClientRepository)
    authorizedClientManager.setAuthorizedClientProvider(authorizedClientProvider)
    return authorizedClientManager
}

You may obtain the OAuth2AccessToken as follows:

  • Java

  • Kotlin

@RestController
public class OAuth2ResourceServerController {

	@Autowired
	private ReactiveOAuth2AuthorizedClientManager authorizedClientManager;

	@GetMapping("/resource")
	public Mono<String> resource(JwtAuthenticationToken jwtAuthentication) {
		OAuth2AuthorizeRequest authorizeRequest = OAuth2AuthorizeRequest.withClientRegistrationId("okta")
				.principal(jwtAuthentication)
				.build();

		return this.authorizedClientManager.authorize(authorizeRequest)
				.map(OAuth2AuthorizedClient::getAccessToken)
				...
	}
}
class OAuth2ResourceServerController {

    @Autowired
    private lateinit var authorizedClientManager: ReactiveOAuth2AuthorizedClientManager

    @GetMapping("/resource")
    fun resource(jwtAuthentication: JwtAuthenticationToken): Mono<String> {
        val authorizeRequest = OAuth2AuthorizeRequest.withClientRegistrationId("okta")
                .principal(jwtAuthentication)
                .build()
        return authorizedClientManager.authorize(authorizeRequest)
                .map { it.accessToken }
                ...
    }
}
TokenExchangeReactiveOAuth2AuthorizedClientProvider resolves the subject token (as an OAuth2Token) via OAuth2AuthorizationContext.getPrincipal().getPrincipal() by default, hence the use of JwtAuthenticationToken in the preceding example. An actor token is not resolved by default.
If you need to resolve the subject token from a different source, you can provide TokenExchangeReactiveOAuth2AuthorizedClientProvider.setSubjectTokenResolver() with a custom Function<OAuth2AuthorizationContext, Mono<OAuth2Token>>.
If you need to resolve an actor token, you can provide TokenExchangeReactiveOAuth2AuthorizedClientProvider.setActorTokenResolver() with a custom Function<OAuth2AuthorizationContext, Mono<OAuth2Token>>.