Add properties for SAML relying party single logout

Closes gh-30128

Co-authored-by: Madhura Bhave <bhavem@vmware.com>

spring-boot-project/spring-boot-docs/src/docs/asciidoc/web/spring-security.adoc

@@ -262,6 +262,10 @@ You can register multiple relying parties under the `spring.security.saml2.relyi
 	              credentials:
 	              - private-key-location: "path-to-private-key"
                     certificate-location: "path-to-certificate"
+                singlelogout:
+                   url: "https://myapp/logout/saml2/slo"
+                   reponse-url: "https://remoteidp2.slo.url"
+                   binding: "POST"
 	            assertingparty:
 	              verification:
 	                credentials:
@@ -284,4 +288,14 @@ You can register multiple relying parties under the `spring.security.saml2.relyi
                     - certificate-location: "path-to-other-verification-cert"
                   entity-id: "remote-idp-entity-id2"
                   sso-url: "https://remoteidp2.sso.url"
+                  singlelogout:
+                    url: "https://remoteidp2.slo.url"
+                    reponse-url: "https://myapp/logout/saml2/slo"
+                    binding: "POST"
 ----
+
+For SAML2 logout, by default, Spring Security's `Saml2LogoutRequestFilter` and `Saml2LogoutResponseFilter` only process URLs matching `/logout/saml2/slo`.
+If you want to customize the `url` to which AP-initiated logout requests get sent to or the `response-url` to which an AP sends logout responses to, to use a different pattern, you need to provide configuration to process that custom pattern.
+For example, for servlet applications, you can add your own `SecurityFilterChain` that resembles the following:
+
+include::code:MySamlRelyingPartyConfiguration[]

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/web/security/saml2/relyingparty/MySamlRelyingPartyConfiguration.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2012-2022 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.boot.docs.web.security.saml2.relyingparty;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.web.SecurityFilterChain;
+
+@Configuration(proxyBeanMethods = false)
+public class MySamlRelyingPartyConfiguration {
+
+	@Bean
+	public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
+		http.authorizeRequests().anyRequest().authenticated();
+		http.saml2Login();
+		http.saml2Logout((saml2) -> saml2.logoutRequest((request) -> request.logoutUrl("/SLOService.saml2"))
+				.logoutResponse((response) -> response.logoutUrl("/SLOService.saml2")));
+		return http.build();
+	}
+
+}