Move AnyRequest Validation

This will make way for other adding other checks

Issue gh-15982

config/src/main/java/org/springframework/security/config/annotation/web/builders/WebSecurity.java

@@ -65,7 +65,6 @@
 import org.springframework.security.web.firewall.ObservationMarkingRequestRejectedHandler;
 import org.springframework.security.web.firewall.RequestRejectedHandler;
 import org.springframework.security.web.firewall.StrictHttpFirewall;
-import org.springframework.security.web.util.matcher.AnyRequestMatcher;
 import org.springframework.security.web.util.matcher.RequestMatcher;
 import org.springframework.security.web.util.matcher.RequestMatcherEntry;
 import org.springframework.util.Assert;
@@ -310,20 +309,8 @@ protected Filter performBuild() throws Exception {
 			requestMatcherPrivilegeEvaluatorsEntries
 				.add(getRequestMatcherPrivilegeEvaluatorsEntry(securityFilterChain));
 		}
-		DefaultSecurityFilterChain anyRequestFilterChain = null;
 		for (SecurityBuilder<? extends SecurityFilterChain> securityFilterChainBuilder : this.securityFilterChainBuilders) {
 			SecurityFilterChain securityFilterChain = securityFilterChainBuilder.build();
-			if (anyRequestFilterChain != null) {
-				String message = "A filter chain that matches any request [" + anyRequestFilterChain
-						+ "] has already been configured, which means that this filter chain [" + securityFilterChain
-						+ "] will never get invoked. Please use `HttpSecurity#securityMatcher` to ensure that there is only one filter chain configured for 'any request' and that the 'any request' filter chain is published last.";
-				throw new IllegalArgumentException(message);
-			}
-			if (securityFilterChain instanceof DefaultSecurityFilterChain defaultSecurityFilterChain) {
-				if (defaultSecurityFilterChain.getRequestMatcher() instanceof AnyRequestMatcher) {
-					anyRequestFilterChain = defaultSecurityFilterChain;
-				}
-			}
 			securityFilterChains.add(securityFilterChain);
 			requestMatcherPrivilegeEvaluatorsEntries
 				.add(getRequestMatcherPrivilegeEvaluatorsEntry(securityFilterChain));
@@ -345,6 +332,7 @@ else if (!this.observationRegistry.isNoop()) {
 					new HttpStatusRequestRejectedHandler());
 			filterChainProxy.setRequestRejectedHandler(requestRejectedHandler);
 		}
+		filterChainProxy.setFilterChainValidator(new WebSecurityFilterChainValidator());
 		filterChainProxy.setFilterChainDecorator(getFilterChainDecorator());
 		filterChainProxy.afterPropertiesSet();
 

config/src/main/java/org/springframework/security/config/annotation/web/builders/WebSecurityFilterChainValidator.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2002-2024 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.config.annotation.web.builders;
+
+import java.util.List;
+
+import org.springframework.security.web.DefaultSecurityFilterChain;
+import org.springframework.security.web.FilterChainProxy;
+import org.springframework.security.web.SecurityFilterChain;
+import org.springframework.security.web.util.matcher.AnyRequestMatcher;
+
+/**
+ * A filter chain validator for filter chains built by {@link WebSecurity}
+ *
+ * @since 6.5
+ */
+final class WebSecurityFilterChainValidator implements FilterChainProxy.FilterChainValidator {
+
+	@Override
+	public void validate(FilterChainProxy filterChainProxy) {
+		List<SecurityFilterChain> chains = filterChainProxy.getFilterChains();
+		DefaultSecurityFilterChain anyRequestFilterChain = null;
+		for (SecurityFilterChain chain : chains) {
+			if (anyRequestFilterChain != null) {
+				String message = "A filter chain that matches any request [" + anyRequestFilterChain
+						+ "] has already been configured, which means that this filter chain [" + chain
+						+ "] will never get invoked. Please use `HttpSecurity#securityMatcher` to ensure that there is only one filter chain configured for 'any request' and that the 'any request' filter chain is published last.";
+				throw new IllegalArgumentException(message);
+			}
+			if (chain instanceof DefaultSecurityFilterChain defaultChain) {
+				if (defaultChain.getRequestMatcher() instanceof AnyRequestMatcher) {
+					anyRequestFilterChain = defaultChain;
+				}
+			}
+		}
+	}
+
+}