Ensure that customizers registered multiple times are only called once

Closes gh-17264

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/reactive/ReactiveWebServerFactoryAutoConfigurationTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.autoconfigure.web.reactive;
 
+import io.undertow.Undertow.Builder;
 import org.apache.catalina.Context;
 import org.apache.catalina.connector.Connector;
 import org.apache.catalina.startup.Tomcat;
@@ -222,6 +223,21 @@ class ReactiveWebServerFactoryAutoConfigurationTests {
 				});
 	}
 
+	@Test
+	void jettyServerCustomizerRegisteredAsBeanAndViaFactoryIsOnlyCalledOnce() {
+		new ReactiveWebApplicationContextRunner(AnnotationConfigReactiveWebServerApplicationContext::new)
+				.withConfiguration(AutoConfigurations.of(ReactiveWebServerFactoryAutoConfiguration.class))
+				.withClassLoader(new FilteredClassLoader(Tomcat.class, HttpServer.class))
+				.withUserConfiguration(DoubleRegistrationJettyServerCustomizerConfiguration.class,
+						HttpHandlerConfiguration.class)
+				.withPropertyValues("server.port=0").run((context) -> {
+					JettyReactiveWebServerFactory factory = context.getBean(JettyReactiveWebServerFactory.class);
+					JettyServerCustomizer customizer = context.getBean("serverCustomizer", JettyServerCustomizer.class);
+					assertThat(factory.getServerCustomizers()).contains(customizer);
+					verify(customizer, times(1)).customize(any(Server.class));
+				});
+	}
+
 	@Test
 	void undertowDeploymentInfoCustomizerBeanIsAddedToFactory() {
 		new ReactiveWebApplicationContextRunner(AnnotationConfigReactiveWebApplicationContext::new)
@@ -247,6 +263,22 @@ class ReactiveWebServerFactoryAutoConfigurationTests {
 				});
 	}
 
+	@Test
+	void undertowBuilderCustomizerRegisteredAsBeanAndViaFactoryIsOnlyCalledOnce() {
+		new ReactiveWebApplicationContextRunner(AnnotationConfigReactiveWebServerApplicationContext::new)
+				.withConfiguration(AutoConfigurations.of(ReactiveWebServerFactoryAutoConfiguration.class))
+				.withClassLoader(new FilteredClassLoader(Tomcat.class, HttpServer.class, Server.class))
+				.withUserConfiguration(DoubleRegistrationUndertowBuilderCustomizerConfiguration.class,
+						HttpHandlerConfiguration.class)
+				.withPropertyValues("server.port: 0").run((context) -> {
+					UndertowReactiveWebServerFactory factory = context.getBean(UndertowReactiveWebServerFactory.class);
+					UndertowBuilderCustomizer customizer = context.getBean("builderCustomizer",
+							UndertowBuilderCustomizer.class);
+					assertThat(factory.getBuilderCustomizers()).contains(customizer);
+					verify(customizer, times(1)).customize(any(Builder.class));
+				});
+	}
+
 	@Test
 	void forwardedHeaderTransformerShouldBeConfigured() {
 		this.contextRunner.withUserConfiguration(HttpHandlerConfiguration.class)
@@ -401,6 +433,23 @@ class ReactiveWebServerFactoryAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class DoubleRegistrationJettyServerCustomizerConfiguration {
+
+		private final JettyServerCustomizer customizer = mock(JettyServerCustomizer.class);
+
+		@Bean
+		JettyServerCustomizer serverCustomizer() {
+			return this.customizer;
+		}
+
+		@Bean
+		WebServerFactoryCustomizer<JettyReactiveWebServerFactory> jettyCustomizer() {
+			return (jetty) -> jetty.addServerCustomizers(this.customizer);
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class UndertowBuilderCustomizerConfiguration {
 
@@ -412,6 +461,23 @@ class ReactiveWebServerFactoryAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class DoubleRegistrationUndertowBuilderCustomizerConfiguration {
+
+		private final UndertowBuilderCustomizer customizer = mock(UndertowBuilderCustomizer.class);
+
+		@Bean
+		UndertowBuilderCustomizer builderCustomizer() {
+			return this.customizer;
+		}
+
+		@Bean
+		WebServerFactoryCustomizer<UndertowReactiveWebServerFactory> undertowCustomizer() {
+			return (undertow) -> undertow.addBuilderCustomizers(this.customizer);
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class UndertowDeploymentInfoCustomizerConfiguration {
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/ServletWebServerFactoryAutoConfigurationTests.java

@@ -22,6 +22,8 @@ import javax.servlet.ServletContext;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
+import io.undertow.Undertow.Builder;
+import io.undertow.servlet.api.DeploymentInfo;
 import org.apache.catalina.Context;
 import org.apache.catalina.connector.Connector;
 import org.apache.catalina.startup.Tomcat;
@@ -163,6 +165,22 @@ class ServletWebServerFactoryAutoConfigurationTests {
 		});
 	}
 
+	@Test
+	void jettyServerCustomizerRegisteredAsBeanAndViaFactoryIsOnlyCalledOnce() {
+		WebApplicationContextRunner runner = new WebApplicationContextRunner(
+				AnnotationConfigServletWebServerApplicationContext::new)
+						.withClassLoader(new FilteredClassLoader(Tomcat.class, HttpServer.class))
+						.withConfiguration(AutoConfigurations.of(ServletWebServerFactoryAutoConfiguration.class))
+						.withUserConfiguration(DoubleRegistrationJettyServerCustomizerConfiguration.class)
+						.withPropertyValues("server.port: 0");
+		runner.run((context) -> {
+			JettyServletWebServerFactory factory = context.getBean(JettyServletWebServerFactory.class);
+			JettyServerCustomizer customizer = context.getBean("serverCustomizer", JettyServerCustomizer.class);
+			assertThat(factory.getServerCustomizers()).contains(customizer);
+			verify(customizer, times(1)).customize(any(Server.class));
+		});
+	}
+
 	@Test
 	void undertowDeploymentInfoCustomizerBeanIsAddedToFactory() {
 		WebApplicationContextRunner runner = new WebApplicationContextRunner(
@@ -177,6 +195,40 @@ class ServletWebServerFactoryAutoConfigurationTests {
 		});
 	}
 
+	@Test
+	void undertowDeploymentInfoCustomizerRegisteredAsBeanAndViaFactoryIsOnlyCalledOnce() {
+		WebApplicationContextRunner runner = new WebApplicationContextRunner(
+				AnnotationConfigServletWebServerApplicationContext::new)
+						.withClassLoader(new FilteredClassLoader(Tomcat.class, HttpServer.class, Server.class))
+						.withConfiguration(AutoConfigurations.of(ServletWebServerFactoryAutoConfiguration.class))
+						.withUserConfiguration(DoubleRegistrationUndertowDeploymentInfoCustomizerConfiguration.class)
+						.withPropertyValues("server.port: 0");
+		runner.run((context) -> {
+			UndertowServletWebServerFactory factory = context.getBean(UndertowServletWebServerFactory.class);
+			UndertowDeploymentInfoCustomizer customizer = context.getBean("deploymentInfoCustomizer",
+					UndertowDeploymentInfoCustomizer.class);
+			assertThat(factory.getDeploymentInfoCustomizers()).contains(customizer);
+			verify(customizer, times(1)).customize(any(DeploymentInfo.class));
+		});
+	}
+
+	@Test
+	void undertowBuilderCustomizerRegisteredAsBeanAndViaFactoryIsOnlyCalledOnce() {
+		WebApplicationContextRunner runner = new WebApplicationContextRunner(
+				AnnotationConfigServletWebServerApplicationContext::new)
+						.withClassLoader(new FilteredClassLoader(Tomcat.class, HttpServer.class, Server.class))
+						.withConfiguration(AutoConfigurations.of(ServletWebServerFactoryAutoConfiguration.class))
+						.withUserConfiguration(DoubleRegistrationUndertowBuilderCustomizerConfiguration.class)
+						.withPropertyValues("server.port: 0");
+		runner.run((context) -> {
+			UndertowServletWebServerFactory factory = context.getBean(UndertowServletWebServerFactory.class);
+			UndertowBuilderCustomizer customizer = context.getBean("builderCustomizer",
+					UndertowBuilderCustomizer.class);
+			assertThat(factory.getBuilderCustomizers()).contains(customizer);
+			verify(customizer, times(1)).customize(any(Builder.class));
+		});
+	}
+
 	@Test
 	void undertowBuilderCustomizerBeanIsAddedToFactory() {
 		WebApplicationContextRunner runner = new WebApplicationContextRunner(
@@ -510,6 +562,23 @@ class ServletWebServerFactoryAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class DoubleRegistrationJettyServerCustomizerConfiguration {
+
+		private final JettyServerCustomizer customizer = mock(JettyServerCustomizer.class);
+
+		@Bean
+		JettyServerCustomizer serverCustomizer() {
+			return this.customizer;
+		}
+
+		@Bean
+		WebServerFactoryCustomizer<JettyServletWebServerFactory> jettyCustomizer() {
+			return (jetty) -> jetty.addServerCustomizers(this.customizer);
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class UndertowBuilderCustomizerConfiguration {
 
@@ -521,6 +590,23 @@ class ServletWebServerFactoryAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class DoubleRegistrationUndertowBuilderCustomizerConfiguration {
+
+		private final UndertowBuilderCustomizer customizer = mock(UndertowBuilderCustomizer.class);
+
+		@Bean
+		UndertowBuilderCustomizer builderCustomizer() {
+			return this.customizer;
+		}
+
+		@Bean
+		WebServerFactoryCustomizer<UndertowServletWebServerFactory> undertowCustomizer() {
+			return (undertow) -> undertow.addBuilderCustomizers(this.customizer);
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class UndertowDeploymentInfoCustomizerConfiguration {
 
@@ -532,6 +618,23 @@ class ServletWebServerFactoryAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class DoubleRegistrationUndertowDeploymentInfoCustomizerConfiguration {
+
+		private final UndertowDeploymentInfoCustomizer customizer = mock(UndertowDeploymentInfoCustomizer.class);
+
+		@Bean
+		UndertowDeploymentInfoCustomizer deploymentInfoCustomizer() {
+			return this.customizer;
+		}
+
+		@Bean
+		WebServerFactoryCustomizer<UndertowServletWebServerFactory> undertowCustomizer() {
+			return (undertow) -> undertow.addDeploymentInfoCustomizers(this.customizer);
+		}
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class ForwardedHeaderFilterConfiguration {