Improve conditions for enabling WebFlux security

This commit correct a mistake where AuthenticationManager was used
instead of ReactiveAuthenticationManager. It also expands the
conditions so that WebFlux security will be enabled when the user
has defined their own SecurityWebFilterChain. In such a situation
no other security-related beans may be needed to use WebFlux
security as things may have been configured directly using the DSL.

Closes gh-37504

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/reactive/ReactiveSecurityAutoConfiguration.java

@@ -29,9 +29,10 @@
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.security.authentication.AuthenticationManager;
+import org.springframework.security.authentication.ReactiveAuthenticationManager;
 import org.springframework.security.config.annotation.web.reactive.EnableWebFluxSecurity;
 import org.springframework.security.core.userdetails.ReactiveUserDetailsService;
+import org.springframework.security.web.server.SecurityWebFilterChain;
 import org.springframework.security.web.server.WebFilterChainProxy;
 import org.springframework.web.reactive.config.WebFluxConfigurer;
 
@@ -54,20 +55,20 @@ public class ReactiveSecurityAutoConfiguration {
 	@Configuration(proxyBeanMethods = false)
 	@ConditionalOnMissingBean(WebFilterChainProxy.class)
 	@ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.REACTIVE)
-	@Conditional(ReactiveAuthenticationManagerCondition.class)
+	@Conditional(EnableWebFluxSecurityCondition.class)
 	@EnableWebFluxSecurity
 	static class EnableWebFluxSecurityConfiguration {
 
 	}
 
-	static final class ReactiveAuthenticationManagerCondition extends AnyNestedCondition {
+	static final class EnableWebFluxSecurityCondition extends AnyNestedCondition {
 
-		ReactiveAuthenticationManagerCondition() {
+		EnableWebFluxSecurityCondition() {
 			super(ConfigurationPhase.REGISTER_BEAN);
 		}
 
-		@ConditionalOnBean(AuthenticationManager.class)
-		static final class ConditionalOnAuthenticationManagerBean {
+		@ConditionalOnBean(ReactiveAuthenticationManager.class)
+		static final class ConditionalOnReactiveAuthenticationManagerBean {
 
 		}
 
@@ -76,6 +77,11 @@ static final class ConditionalOnReactiveUserDetailsService {
 
 		}
 
+		@ConditionalOnBean(SecurityWebFilterChain.class)
+		static final class ConditionalOnSecurityWebFilterChain {
+
+		}
+
 	}
 
 }

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/reactive/ReactiveSecurityAutoConfigurationTests.java

@@ -25,9 +25,11 @@
 import org.springframework.boot.test.context.runner.ReactiveWebApplicationContextRunner;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.security.authentication.ReactiveAuthenticationManager;
 import org.springframework.security.config.annotation.web.reactive.EnableWebFluxSecurity;
 import org.springframework.security.core.userdetails.MapReactiveUserDetailsService;
 import org.springframework.security.core.userdetails.User;
+import org.springframework.security.web.server.SecurityWebFilterChain;
 import org.springframework.security.web.server.WebFilterChainProxy;
 import org.springframework.web.reactive.config.WebFluxConfigurer;
 
@@ -57,11 +59,24 @@ void backsOffWhenReactiveAuthenticationManagerNotPresent() {
 	}
 
 	@Test
-	void enablesWebFluxSecurity() {
+	void enablesWebFluxSecurityWhenUserDetailsServiceIsPresent() {
 		this.contextRunner.withUserConfiguration(UserDetailsServiceConfiguration.class)
 			.run((context) -> assertThat(context).getBean(WebFilterChainProxy.class).isNotNull());
 	}
 
+	@Test
+	void enablesWebFluxSecurityWhenReactiveAuthenticationManagerIsPresent() {
+		this.contextRunner
+			.withBean(ReactiveAuthenticationManager.class, () -> mock(ReactiveAuthenticationManager.class))
+			.run((context) -> assertThat(context).getBean(WebFilterChainProxy.class).isNotNull());
+	}
+
+	@Test
+	void enablesWebFluxSecurityWhenSecurityWebFilterChainIsPresent() {
+		this.contextRunner.withBean(SecurityWebFilterChain.class, () -> mock(SecurityWebFilterChain.class))
+			.run((context) -> assertThat(context).getBean(WebFilterChainProxy.class).isNotNull());
+	}
+
 	@Test
 	void autoConfigurationIsConditionalOnClass() {
 		this.contextRunner