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 {
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/jetty/JettyReactiveWebServerFactory.java

@@ -17,10 +17,10 @@
 package org.springframework.boot.web.embedded.jetty;
 
 import java.net.InetSocketAddress;
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.List;
+import java.util.LinkedHashSet;
+import java.util.Set;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -68,7 +68,7 @@ public class JettyReactiveWebServerFactory extends AbstractReactiveWebServerFact
 
 	private boolean useForwardHeaders;
 
-	private List<JettyServerCustomizer> jettyServerCustomizers = new ArrayList<>();
+	private Set<JettyServerCustomizer> jettyServerCustomizers = new LinkedHashSet<>();
 
 	private JettyResourceFactory resourceFactory;
 
@@ -119,7 +119,7 @@ public class JettyReactiveWebServerFactory extends AbstractReactiveWebServerFact
 	 */
 	public void setServerCustomizers(Collection<? extends JettyServerCustomizer> customizers) {
 		Assert.notNull(customizers, "Customizers must not be null");
-		this.jettyServerCustomizers = new ArrayList<>(customizers);
+		this.jettyServerCustomizers = new LinkedHashSet<>(customizers);
 	}
 
 	/**

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/jetty/JettyServletWebServerFactory.java

@@ -27,7 +27,9 @@ import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Set;
 
 import org.eclipse.jetty.http.MimeTypes;
 import org.eclipse.jetty.server.AbstractConnector;
@@ -101,7 +103,7 @@ public class JettyServletWebServerFactory extends AbstractServletWebServerFactor
 	 */
 	private int selectors = -1;
 
-	private List<JettyServerCustomizer> jettyServerCustomizers = new ArrayList<>();
+	private Set<JettyServerCustomizer> jettyServerCustomizers = new LinkedHashSet<>();
 
 	private ResourceLoader resourceLoader;
 
@@ -425,7 +427,7 @@ public class JettyServletWebServerFactory extends AbstractServletWebServerFactor
 	 */
 	public void setServerCustomizers(Collection<? extends JettyServerCustomizer> customizers) {
 		Assert.notNull(customizers, "Customizers must not be null");
-		this.jettyServerCustomizers = new ArrayList<>(customizers);
+		this.jettyServerCustomizers = new LinkedHashSet<>(customizers);
 	}
 
 	/**

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/tomcat/TomcatReactiveWebServerFactory.java

@@ -24,6 +24,7 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Set;
 
 import org.apache.catalina.Context;
 import org.apache.catalina.Engine;
@@ -72,11 +73,11 @@ public class TomcatReactiveWebServerFactory extends AbstractReactiveWebServerFac
 
 	private List<LifecycleListener> contextLifecycleListeners = getDefaultLifecycleListeners();
 
-	private Collection<TomcatContextCustomizer> tomcatContextCustomizers = new LinkedHashSet<>();
+	private Set<TomcatContextCustomizer> tomcatContextCustomizers = new LinkedHashSet<>();
 
-	private Collection<TomcatConnectorCustomizer> tomcatConnectorCustomizers = new LinkedHashSet<>();
+	private Set<TomcatConnectorCustomizer> tomcatConnectorCustomizers = new LinkedHashSet<>();
 
-	private Collection<TomcatProtocolHandlerCustomizer<?>> tomcatProtocolHandlerCustomizers = new LinkedHashSet<>();
+	private Set<TomcatProtocolHandlerCustomizer<?>> tomcatProtocolHandlerCustomizers = new LinkedHashSet<>();
 
 	private final List<Connector> additionalTomcatConnectors = new ArrayList<>();
 
@@ -234,7 +235,7 @@ public class TomcatReactiveWebServerFactory extends AbstractReactiveWebServerFac
 	 */
 	public void setTomcatContextCustomizers(Collection<? extends TomcatContextCustomizer> tomcatContextCustomizers) {
 		Assert.notNull(tomcatContextCustomizers, "TomcatContextCustomizers must not be null");
-		this.tomcatContextCustomizers = new ArrayList<>(tomcatContextCustomizers);
+		this.tomcatContextCustomizers = new LinkedHashSet<>(tomcatContextCustomizers);
 	}
 
 	/**
@@ -265,7 +266,7 @@ public class TomcatReactiveWebServerFactory extends AbstractReactiveWebServerFac
 	public void setTomcatConnectorCustomizers(
 			Collection<? extends TomcatConnectorCustomizer> tomcatConnectorCustomizers) {
 		Assert.notNull(tomcatConnectorCustomizers, "TomcatConnectorCustomizers must not be null");
-		this.tomcatConnectorCustomizers = new ArrayList<>(tomcatConnectorCustomizers);
+		this.tomcatConnectorCustomizers = new LinkedHashSet<>(tomcatConnectorCustomizers);
 	}
 
 	/**
@@ -297,7 +298,7 @@ public class TomcatReactiveWebServerFactory extends AbstractReactiveWebServerFac
 	public void setTomcatProtocolHandlerCustomizers(
 			Collection<? extends TomcatProtocolHandlerCustomizer<?>> tomcatProtocolHandlerCustomizers) {
 		Assert.notNull(tomcatProtocolHandlerCustomizers, "TomcatProtocolHandlerCustomizers must not be null");
-		this.tomcatProtocolHandlerCustomizers = new ArrayList<>(tomcatProtocolHandlerCustomizers);
+		this.tomcatProtocolHandlerCustomizers = new LinkedHashSet<>(tomcatProtocolHandlerCustomizers);
 	}
 
 	/**

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/tomcat/TomcatServletWebServerFactory.java

@@ -116,11 +116,11 @@ public class TomcatServletWebServerFactory extends AbstractServletWebServerFacto
 
 	private List<LifecycleListener> contextLifecycleListeners = getDefaultLifecycleListeners();
 
-	private Collection<TomcatContextCustomizer> tomcatContextCustomizers = new LinkedHashSet<>();
+	private Set<TomcatContextCustomizer> tomcatContextCustomizers = new LinkedHashSet<>();
 
-	private Collection<TomcatConnectorCustomizer> tomcatConnectorCustomizers = new LinkedHashSet<>();
+	private Set<TomcatConnectorCustomizer> tomcatConnectorCustomizers = new LinkedHashSet<>();
 
-	private Collection<TomcatProtocolHandlerCustomizer<?>> tomcatProtocolHandlerCustomizers = new LinkedHashSet<>();
+	private Set<TomcatProtocolHandlerCustomizer<?>> tomcatProtocolHandlerCustomizers = new LinkedHashSet<>();
 
 	private final List<Connector> additionalTomcatConnectors = new ArrayList<>();
 
@@ -569,7 +569,7 @@ public class TomcatServletWebServerFactory extends AbstractServletWebServerFacto
 	 */
 	public void setTomcatContextCustomizers(Collection<? extends TomcatContextCustomizer> tomcatContextCustomizers) {
 		Assert.notNull(tomcatContextCustomizers, "TomcatContextCustomizers must not be null");
-		this.tomcatContextCustomizers = new ArrayList<>(tomcatContextCustomizers);
+		this.tomcatContextCustomizers = new LinkedHashSet<>(tomcatContextCustomizers);
 	}
 
 	/**
@@ -595,7 +595,7 @@ public class TomcatServletWebServerFactory extends AbstractServletWebServerFacto
 	public void setTomcatConnectorCustomizers(
 			Collection<? extends TomcatConnectorCustomizer> tomcatConnectorCustomizers) {
 		Assert.notNull(tomcatConnectorCustomizers, "TomcatConnectorCustomizers must not be null");
-		this.tomcatConnectorCustomizers = new ArrayList<>(tomcatConnectorCustomizers);
+		this.tomcatConnectorCustomizers = new LinkedHashSet<>(tomcatConnectorCustomizers);
 	}
 
 	@Override
@@ -622,7 +622,7 @@ public class TomcatServletWebServerFactory extends AbstractServletWebServerFacto
 	public void setTomcatProtocolHandlerCustomizers(
 			Collection<? extends TomcatProtocolHandlerCustomizer<?>> tomcatProtocolHandlerCustomizer) {
 		Assert.notNull(tomcatProtocolHandlerCustomizer, "TomcatProtocolHandlerCustomizers must not be null");
-		this.tomcatProtocolHandlerCustomizers = new ArrayList<>(tomcatProtocolHandlerCustomizer);
+		this.tomcatProtocolHandlerCustomizers = new LinkedHashSet<>(tomcatProtocolHandlerCustomizer);
 	}
 
 	/**

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowReactiveWebServerFactory.java

@@ -22,7 +22,9 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Set;
 import java.util.concurrent.TimeUnit;
 
 import io.undertow.Handlers;
@@ -52,7 +54,7 @@ import org.springframework.util.Assert;
 public class UndertowReactiveWebServerFactory extends AbstractReactiveWebServerFactory
 		implements ConfigurableUndertowWebServerFactory {
 
-	private List<UndertowBuilderCustomizer> builderCustomizers = new ArrayList<>();
+	private Set<UndertowBuilderCustomizer> builderCustomizers = new LinkedHashSet<>();
 
 	private List<UndertowDeploymentInfoCustomizer> deploymentInfoCustomizers = new ArrayList<>();
 
@@ -295,7 +297,7 @@ public class UndertowReactiveWebServerFactory extends AbstractReactiveWebServerF
 	 */
 	public void setBuilderCustomizers(Collection<? extends UndertowBuilderCustomizer> customizers) {
 		Assert.notNull(customizers, "Customizers must not be null");
-		this.builderCustomizers = new ArrayList<>(customizers);
+		this.builderCustomizers = new LinkedHashSet<>(customizers);
 	}
 
 	/**

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/UndertowServletWebServerFactory.java

@@ -26,6 +26,7 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.EventListener;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
@@ -92,9 +93,9 @@ public class UndertowServletWebServerFactory extends AbstractServletWebServerFac
 
 	private static final Set<Class<?>> NO_CLASSES = Collections.emptySet();
 
-	private List<UndertowBuilderCustomizer> builderCustomizers = new ArrayList<>();
+	private Set<UndertowBuilderCustomizer> builderCustomizers = new LinkedHashSet<>();
 
-	private List<UndertowDeploymentInfoCustomizer> deploymentInfoCustomizers = new ArrayList<>();
+	private Set<UndertowDeploymentInfoCustomizer> deploymentInfoCustomizers = new LinkedHashSet<>();
 
 	private ResourceLoader resourceLoader;
 
@@ -157,7 +158,7 @@ public class UndertowServletWebServerFactory extends AbstractServletWebServerFac
 	 */
 	public void setBuilderCustomizers(Collection<? extends UndertowBuilderCustomizer> customizers) {
 		Assert.notNull(customizers, "Customizers must not be null");
-		this.builderCustomizers = new ArrayList<>(customizers);
+		this.builderCustomizers = new LinkedHashSet<>(customizers);
 	}
 
 	/**
@@ -183,7 +184,7 @@ public class UndertowServletWebServerFactory extends AbstractServletWebServerFac
 	 */
 	public void setDeploymentInfoCustomizers(Collection<? extends UndertowDeploymentInfoCustomizer> customizers) {
 		Assert.notNull(customizers, "Customizers must not be null");
-		this.deploymentInfoCustomizers = new ArrayList<>(customizers);
+		this.deploymentInfoCustomizers = new LinkedHashSet<>(customizers);
 	}
 
 	/**