Add token-exchange to grant_types_supported

Issue gh-1525

Author: sjohnr

oauth2-authorization-server/src/main/java/org/springframework/security/oauth2/server/authorization/oidc/web/OidcProviderConfigurationEndpointFilter.java

@@ -105,6 +105,8 @@ protected void doFilterInternal(HttpServletRequest request, HttpServletResponse
 				.grantType(AuthorizationGrantType.CLIENT_CREDENTIALS.getValue())
 				.grantType(AuthorizationGrantType.REFRESH_TOKEN.getValue())
 				.grantType(AuthorizationGrantType.DEVICE_CODE.getValue())
+				// TODO: Replace with constant from spring-security:
+				.grantType(new AuthorizationGrantType("urn:ietf:params:oauth:grant-type:token-exchange").getValue())
 				.tokenRevocationEndpoint(asUrl(issuer, authorizationServerSettings.getTokenRevocationEndpoint()))
 				.tokenRevocationEndpointAuthenticationMethods(clientAuthenticationMethods())
 				.tokenIntrospectionEndpoint(asUrl(issuer, authorizationServerSettings.getTokenIntrospectionEndpoint()))

oauth2-authorization-server/src/main/java/org/springframework/security/oauth2/server/authorization/web/OAuth2AuthorizationServerMetadataEndpointFilter.java

@@ -101,6 +101,8 @@ protected void doFilterInternal(HttpServletRequest request, HttpServletResponse
 				.grantType(AuthorizationGrantType.CLIENT_CREDENTIALS.getValue())
 				.grantType(AuthorizationGrantType.REFRESH_TOKEN.getValue())
 				.grantType(AuthorizationGrantType.DEVICE_CODE.getValue())
+				// TODO: Replace with constant from spring-security:
+				.grantType(new AuthorizationGrantType("urn:ietf:params:oauth:grant-type:token-exchange").getValue())
 				.tokenRevocationEndpoint(asUrl(issuer, authorizationServerSettings.getTokenRevocationEndpoint()))
 				.tokenRevocationEndpointAuthenticationMethods(clientAuthenticationMethods())
 				.tokenIntrospectionEndpoint(asUrl(issuer, authorizationServerSettings.getTokenIntrospectionEndpoint()))

oauth2-authorization-server/src/test/java/org/springframework/security/oauth2/server/authorization/oidc/web/OidcProviderConfigurationEndpointFilterTests.java

@@ -18,7 +18,6 @@
 import jakarta.servlet.FilterChain;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
-
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 
@@ -126,7 +125,7 @@ public void doFilterWhenConfigurationRequestThenConfigurationResponse() throws E
 		assertThat(providerConfigurationResponse).contains("\"jwks_uri\":\"https://example.com/oauth2/v1/jwks\"");
 		assertThat(providerConfigurationResponse).contains("\"scopes_supported\":[\"openid\"]");
 		assertThat(providerConfigurationResponse).contains("\"response_types_supported\":[\"code\"]");
-		assertThat(providerConfigurationResponse).contains("\"grant_types_supported\":[\"authorization_code\",\"client_credentials\",\"refresh_token\",\"urn:ietf:params:oauth:grant-type:device_code\"]");
+		assertThat(providerConfigurationResponse).contains("\"grant_types_supported\":[\"authorization_code\",\"client_credentials\",\"refresh_token\",\"urn:ietf:params:oauth:grant-type:device_code\",\"urn:ietf:params:oauth:grant-type:token-exchange\"]");
 		assertThat(providerConfigurationResponse).contains("\"revocation_endpoint\":\"https://example.com/oauth2/v1/revoke\"");
 		assertThat(providerConfigurationResponse).contains("\"revocation_endpoint_auth_methods_supported\":[\"client_secret_basic\",\"client_secret_post\",\"client_secret_jwt\",\"private_key_jwt\"]");
 		assertThat(providerConfigurationResponse).contains("\"introspection_endpoint\":\"https://example.com/oauth2/v1/introspect\"");

oauth2-authorization-server/src/test/java/org/springframework/security/oauth2/server/authorization/web/OAuth2AuthorizationServerMetadataEndpointFilterTests.java

@@ -18,7 +18,6 @@
 import jakarta.servlet.FilterChain;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
-
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 
@@ -122,7 +121,7 @@ public void doFilterWhenAuthorizationServerMetadataRequestThenMetadataResponse()
 		assertThat(authorizationServerMetadataResponse).contains("\"token_endpoint_auth_methods_supported\":[\"client_secret_basic\",\"client_secret_post\",\"client_secret_jwt\",\"private_key_jwt\"]");
 		assertThat(authorizationServerMetadataResponse).contains("\"jwks_uri\":\"https://example.com/oauth2/v1/jwks\"");
 		assertThat(authorizationServerMetadataResponse).contains("\"response_types_supported\":[\"code\"]");
-		assertThat(authorizationServerMetadataResponse).contains("\"grant_types_supported\":[\"authorization_code\",\"client_credentials\",\"refresh_token\",\"urn:ietf:params:oauth:grant-type:device_code\"]");
+		assertThat(authorizationServerMetadataResponse).contains("\"grant_types_supported\":[\"authorization_code\",\"client_credentials\",\"refresh_token\",\"urn:ietf:params:oauth:grant-type:device_code\",\"urn:ietf:params:oauth:grant-type:token-exchange\"]");
 		assertThat(authorizationServerMetadataResponse).contains("\"revocation_endpoint\":\"https://example.com/oauth2/v1/revoke\"");
 		assertThat(authorizationServerMetadataResponse).contains("\"revocation_endpoint_auth_methods_supported\":[\"client_secret_basic\",\"client_secret_post\",\"client_secret_jwt\",\"private_key_jwt\"]");
 		assertThat(authorizationServerMetadataResponse).contains("\"introspection_endpoint\":\"https://example.com/oauth2/v1/introspect\"");