Add missing ClientAuthenticationMethods to jackson2 converter

Closes gh-16825

Signed-off-by: Risto Virtanen <818702+mapsu@users.noreply.github.com>

oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/jackson2/StdConverters.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -56,9 +56,21 @@ abstract class StdConverters {
 			if (ClientAuthenticationMethod.CLIENT_SECRET_POST.getValue().equalsIgnoreCase(value)) {
 				return ClientAuthenticationMethod.CLIENT_SECRET_POST;
 			}
+			if (ClientAuthenticationMethod.CLIENT_SECRET_JWT.getValue().equalsIgnoreCase(value)) {
+				return ClientAuthenticationMethod.CLIENT_SECRET_JWT;
+			}
+			if (ClientAuthenticationMethod.PRIVATE_KEY_JWT.getValue().equalsIgnoreCase(value)) {
+				return ClientAuthenticationMethod.PRIVATE_KEY_JWT;
+			}
 			if (ClientAuthenticationMethod.NONE.getValue().equalsIgnoreCase(value)) {
 				return ClientAuthenticationMethod.NONE;
 			}
+			if (ClientAuthenticationMethod.TLS_CLIENT_AUTH.getValue().equalsIgnoreCase(value)) {
+				return ClientAuthenticationMethod.TLS_CLIENT_AUTH;
+			}
+			if (ClientAuthenticationMethod.SELF_SIGNED_TLS_CLIENT_AUTH.getValue().equalsIgnoreCase(value)) {
+				return ClientAuthenticationMethod.SELF_SIGNED_TLS_CLIENT_AUTH;
+			}
 			return null;
 		}
 

oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/jackson2/ClientRegistrationMixinTests.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright 2002-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.security.oauth2.client.jackson2;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+import org.springframework.security.jackson2.SecurityJackson2Modules;
+import org.springframework.security.oauth2.client.registration.ClientRegistration;
+import org.springframework.security.oauth2.client.registration.TestClientRegistrations;
+import org.springframework.security.oauth2.core.ClientAuthenticationMethod;
+
+import java.util.stream.Stream;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class ClientRegistrationMixinTests {
+
+	private ObjectMapper mapper;
+
+	@BeforeEach
+	void setUp() {
+		ClassLoader loader = getClass().getClassLoader();
+		this.mapper = new ObjectMapper();
+		this.mapper.registerModules(SecurityJackson2Modules.getModules(loader));
+	}
+
+	@ParameterizedTest
+	@MethodSource("deserializeWhenMixinRegisteredThenDeserializes")
+	void deserializeWhenMixinRegisteredThenDeserializes(
+			ClientRegistration expectedClientRegistration
+	) throws Exception {
+		String json = asJson(expectedClientRegistration);
+		ClientRegistration clientRegistration = this.mapper.readValue(json, ClientRegistration.class);
+		assertThat(clientRegistration.getClientAuthenticationMethod()).isEqualTo(expectedClientRegistration.getClientAuthenticationMethod());
+	}
+
+	private String asJson(ClientRegistration expectedClientRegistration) {
+		// @formatter:off
+		return "{" +
+				"  \"@class\":\"org.springframework.security.oauth2.client.registration.ClientRegistration\"," +
+				"  \"registrationId\":\"registration-id\"," +
+				"  \"clientId\":\"client-id\"," +
+				"  \"clientSecret\":\"client-secret\"," +
+				"  \"clientAuthenticationMethod\":{" +
+				"    \"value\":\"" + expectedClientRegistration.getClientAuthenticationMethod().getValue() + "\"" +
+				"  }," +
+				"  \"authorizationGrantType\":{" +
+				"    \"value\":\"" + expectedClientRegistration.getAuthorizationGrantType().getValue() + "\"" +
+				"  }," +
+				"  \"redirectUri\":\"{baseUrl}/{action}/oauth2/code/{registrationId}\"," +
+				"  \"scopes\":[" +
+				"    \"java.util.Collections$UnmodifiableSet\",[\"read:user\"]" +
+				"  ]," +
+				"  \"providerDetails\":{" +
+				"    \"@class\":\"org.springframework.security.oauth2.client.registration.ClientRegistration$ProviderDetails\"," +
+				"    \"authorizationUri\":\"https://example.com/login/oauth/authorize\"," +
+				"    \"tokenUri\": \"https://example.com/login/oauth/access_token\"," +
+				"    \"userInfoEndpoint\":{" +
+				"      \"@class\":\"org.springframework.security.oauth2.client.registration.ClientRegistration$ProviderDetails$UserInfoEndpoint\"," +
+				"      \"uri\":\"https://api.example.com/user\"," +
+				"      \"authenticationMethod\":{" +
+				"        \"value\":\"header\"" +
+				"      }," +
+				"      \"userNameAttributeName\":\"id\"" +
+				"    }," +
+				"    \"jwkSetUri\":\"https://example.com/oauth2/jwk\"," +
+				"    \"issuerUri\":\"https://example.com\"," +
+				"    \"configurationMetadata\":{" +
+				"      \"@class\":\"java.util.Collections$UnmodifiableMap\"" +
+				"    }" +
+				"  }," +
+				"  \"clientName\":\"Client Name\"}";
+		// @formatter:on
+	}
+
+	static Stream<Arguments> deserializeWhenMixinRegisteredThenDeserializes() {
+		return Stream.of(
+				Arguments.of(
+						TestClientRegistrations.clientRegistration()
+								.clientAuthenticationMethod(ClientAuthenticationMethod.CLIENT_SECRET_POST)
+								.build()
+				),
+				Arguments.of(
+						TestClientRegistrations.clientRegistration()
+								.clientAuthenticationMethod(ClientAuthenticationMethod.PRIVATE_KEY_JWT)
+								.build()
+				),
+				Arguments.of(
+						TestClientRegistrations.clientRegistration()
+								.clientAuthenticationMethod(ClientAuthenticationMethod.NONE)
+								.build()
+				)
+		);
+	}
+}