feat(deps): upgrade to Spring Boot 4

.gitignore

@@ -7,6 +7,7 @@ target/
 .project
 .factorypath
 .apt_generated/
+.checkstyle
 
 # Intellij
 .idea/
@@ -28,3 +29,4 @@ node/
 
 .DS_Store
 mockServiceWorker.js
+/.github/agents/

pom.xml

@@ -30,10 +30,10 @@
     <url>https://github.com/codecentric/spring-boot-admin/</url>
 
     <properties>
-        <revision>3.5.7-SNAPSHOT</revision>
+        <revision>4.0.0-M1-SNAPSHOT</revision>
 
         <java.version>17</java.version>
-        <node.version>v22.12.0</node.version>
+        <node.version>v22.14.0</node.version>
 
         <require.maven.version>3.9</require.maven.version>
 
@@ -47,10 +47,11 @@
         <maven.site.skip>true</maven.site.skip>
 
         <!-- used dependencies versions -->
-        <spring-boot.version>3.5.8</spring-boot.version>
-        <spring-cloud.version>2025.0.0</spring-cloud.version>
+        <spring-boot.version>4.0.0</spring-boot.version>
+        <spring-cloud.version>2025.1.0</spring-cloud.version>
 
-        <jolokia-support-spring.version>2.4.2</jolokia-support-spring.version>
+        <!-- FIXME downgrade to 2.1.0 until a compatible version is released -->
+        <jolokia-support-spring.version>2.1.0</jolokia-support-spring.version>
 
         <checkstyle.version>12.2.0</checkstyle.version>
         <findbugs-jsr305.version>3.0.2</findbugs-jsr305.version>

spring-boot-admin-client/pom.xml

@@ -34,21 +34,36 @@
     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-starter</artifactId>
+            <artifactId>spring-boot-starter-classic</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-actuator</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
-            <artifactId>spring-web</artifactId>
+            <artifactId>spring-webmvc</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-restclient</artifactId>
+            <optional>true</optional>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-webclient</artifactId>
+            <optional>true</optional>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>
             <optional>true</optional>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-webflux</artifactId>
+            <optional>true</optional>
+        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-autoconfigure-processor</artifactId>
@@ -64,6 +79,10 @@
             <artifactId>spring-webflux</artifactId>
             <optional>true</optional>
         </dependency>
+        <dependency>
+            <groupId>com.google.code.findbugs</groupId>
+            <artifactId>jsr305</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
@@ -74,11 +93,6 @@
             <artifactId>spring-boot-starter-test</artifactId>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-starter-webflux</artifactId>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>org.wiremock</groupId>
             <artifactId>wiremock-standalone</artifactId>
@@ -89,5 +103,10 @@
             <artifactId>awaitility</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 </project>

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/config/ClientRuntimeHints.java

@@ -21,7 +21,7 @@
 import org.springframework.aot.hint.MemberCategory;
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.RuntimeHintsRegistrar;
-import org.springframework.boot.web.context.WebServerInitializedEvent;
+import org.springframework.boot.web.server.context.WebServerInitializedEvent;
 import org.springframework.context.annotation.Configuration;
 
 import de.codecentric.boot.admin.client.registration.Application;

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/config/SpringBootAdminClientAutoConfiguration.java

@@ -29,17 +29,18 @@
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
-import org.springframework.boot.autoconfigure.web.ServerProperties;
-import org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration;
-import org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration;
-import org.springframework.boot.autoconfigure.web.reactive.WebFluxProperties;
-import org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration;
-import org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration;
-import org.springframework.boot.autoconfigure.web.servlet.DispatcherServletPath;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication.Type;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
-import org.springframework.boot.http.client.ClientHttpRequestFactorySettings;
-import org.springframework.boot.web.client.RestTemplateBuilder;
+import org.springframework.boot.http.client.HttpClientSettings;
+import org.springframework.boot.restclient.RestTemplateBuilder;
+import org.springframework.boot.restclient.autoconfigure.RestClientAutoConfiguration;
+import org.springframework.boot.restclient.autoconfigure.RestTemplateAutoConfiguration;
+import org.springframework.boot.web.server.autoconfigure.ServerProperties;
+import org.springframework.boot.webclient.autoconfigure.WebClientAutoConfiguration;
+import org.springframework.boot.webflux.autoconfigure.WebFluxProperties;
+import org.springframework.boot.webmvc.autoconfigure.DispatcherServletAutoConfiguration;
+import org.springframework.boot.webmvc.autoconfigure.DispatcherServletPath;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
@@ -64,7 +65,6 @@
 import de.codecentric.boot.admin.client.registration.metadata.MetadataContributor;
 import de.codecentric.boot.admin.client.registration.metadata.StartupDateMetadataContributor;
 
-import static org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication.Type;
 import static org.springframework.web.reactive.function.client.ExchangeFilterFunctions.basicAuthentication;
 
 @Configuration(proxyBeanMethods = false)
@@ -159,22 +159,25 @@ public RegistrationClient registrationClient(ClientProperties client) {
 	}
 
 	@Configuration(proxyBeanMethods = false)
-	@ConditionalOnBean({ RestClient.Builder.class, ClientHttpRequestFactoryBuilder.class })
+	@ConditionalOnBean(RestClient.Builder.class)
 	public static class RestClientRegistrationClientConfig {
 
 		@Bean
 		@ConditionalOnMissingBean
-		public RegistrationClient registrationClient(ClientProperties client, RestClient.Builder restClientBuilder,
-				ClientHttpRequestFactoryBuilder<?> clientHttpRequestFactoryBuilder) {
-			var factorySettings = ClientHttpRequestFactorySettings.defaults()
+		public RegistrationClient registrationClient(ClientProperties client, RestClient.Builder restClientBuilder) {
+			var factorySettings = HttpClientSettings.defaults()
 				.withConnectTimeout(client.getConnectTimeout())
 				.withReadTimeout(client.getReadTimeout());
-			var clientHttpRequestFactory = clientHttpRequestFactoryBuilder.build(factorySettings);
+
+			var clientHttpRequestFactory = ClientHttpRequestFactoryBuilder.detect().build(factorySettings);
+
 			restClientBuilder = restClientBuilder.requestFactory(clientHttpRequestFactory);
+
 			if (client.getUsername() != null && client.getPassword() != null) {
 				restClientBuilder = restClientBuilder
 					.requestInterceptor(new BasicAuthenticationInterceptor(client.getUsername(), client.getPassword()));
 			}
+
 			var restClient = restClientBuilder.build();
 			return new RestClientRegistrationClient(restClient);
 		}

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/config/SpringBootAdminClientCloudFoundryAutoConfiguration.java

@@ -27,9 +27,9 @@
 import org.springframework.boot.autoconfigure.condition.ConditionalOnCloudPlatform;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
-import org.springframework.boot.autoconfigure.web.ServerProperties;
 import org.springframework.boot.cloud.CloudPlatform;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.boot.web.server.autoconfigure.ServerProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/config/SpringNativeClientAutoConfiguration.java

@@ -19,8 +19,8 @@
 import org.springframework.boot.actuate.autoconfigure.endpoint.web.WebEndpointAutoConfiguration;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
-import org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration;
-import org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration;
+import org.springframework.boot.restclient.autoconfigure.RestTemplateAutoConfiguration;
+import org.springframework.boot.webclient.autoconfigure.WebClientAutoConfiguration;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.ImportRuntimeHints;

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/registration/CloudFoundryApplicationFactory.java

@@ -19,7 +19,7 @@
 import org.springframework.boot.actuate.autoconfigure.endpoint.web.WebEndpointProperties;
 import org.springframework.boot.actuate.autoconfigure.web.server.ManagementServerProperties;
 import org.springframework.boot.actuate.endpoint.web.PathMappedEndpoints;
-import org.springframework.boot.autoconfigure.web.ServerProperties;
+import org.springframework.boot.web.server.autoconfigure.ServerProperties;
 import org.springframework.util.StringUtils;
 
 import de.codecentric.boot.admin.client.config.CloudFoundryApplicationProperties;

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/registration/DefaultApplicationFactory.java

@@ -25,9 +25,9 @@
 import org.springframework.boot.actuate.autoconfigure.web.server.ManagementServerProperties;
 import org.springframework.boot.actuate.endpoint.EndpointId;
 import org.springframework.boot.actuate.endpoint.web.PathMappedEndpoints;
-import org.springframework.boot.autoconfigure.web.ServerProperties;
-import org.springframework.boot.web.context.WebServerInitializedEvent;
 import org.springframework.boot.web.server.Ssl;
+import org.springframework.boot.web.server.autoconfigure.ServerProperties;
+import org.springframework.boot.web.server.context.WebServerInitializedEvent;
 import org.springframework.context.event.EventListener;
 import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/registration/ReactiveApplicationFactory.java

@@ -19,9 +19,9 @@
 import org.springframework.boot.actuate.autoconfigure.endpoint.web.WebEndpointProperties;
 import org.springframework.boot.actuate.autoconfigure.web.server.ManagementServerProperties;
 import org.springframework.boot.actuate.endpoint.web.PathMappedEndpoints;
-import org.springframework.boot.autoconfigure.web.ServerProperties;
-import org.springframework.boot.autoconfigure.web.reactive.WebFluxProperties;
 import org.springframework.boot.web.server.Ssl;
+import org.springframework.boot.web.server.autoconfigure.ServerProperties;
+import org.springframework.boot.webflux.autoconfigure.WebFluxProperties;
 import org.springframework.util.StringUtils;
 import org.springframework.web.util.UriComponentsBuilder;
 

spring-boot-admin-client/src/main/java/de/codecentric/boot/admin/client/registration/ServletApplicationFactory.java

@@ -20,9 +20,9 @@
 import org.springframework.boot.actuate.autoconfigure.endpoint.web.WebEndpointProperties;
 import org.springframework.boot.actuate.autoconfigure.web.server.ManagementServerProperties;
 import org.springframework.boot.actuate.endpoint.web.PathMappedEndpoints;
-import org.springframework.boot.autoconfigure.web.ServerProperties;
-import org.springframework.boot.autoconfigure.web.servlet.DispatcherServletPath;
 import org.springframework.boot.web.server.Ssl;
+import org.springframework.boot.web.server.autoconfigure.ServerProperties;
+import org.springframework.boot.webmvc.autoconfigure.DispatcherServletPath;
 import org.springframework.util.StringUtils;
 import org.springframework.web.util.UriComponentsBuilder;
 
@@ -55,8 +55,8 @@ public ServletApplicationFactory(InstanceProperties instance, ManagementServerPr
 
 	@Override
 	protected String getServiceUrl() {
-		if (instance.getServiceUrl() != null) {
-			return instance.getServiceUrl();
+		if (this.instance.getServiceUrl() != null) {
+			return this.instance.getServiceUrl();
 		}
 
 		return UriComponentsBuilder.fromUriString(getServiceBaseUrl())
@@ -67,7 +67,7 @@ protected String getServiceUrl() {
 
 	@Override
 	protected String getManagementBaseUrl() {
-		String baseUrl = instance.getManagementBaseUrl();
+		String baseUrl = this.instance.getManagementBaseUrl();
 
 		if (StringUtils.hasText(baseUrl)) {
 			return baseUrl;
@@ -81,7 +81,7 @@ protected String getManagementBaseUrl() {
 				.toUriString();
 		}
 
-		Ssl ssl = (management.getSsl() != null) ? management.getSsl() : server.getSsl();
+		Ssl ssl = (this.management.getSsl() != null) ? this.management.getSsl() : this.server.getSsl();
 		return UriComponentsBuilder.newInstance()
 			.scheme(getScheme(ssl))
 			.host(getManagementHost())
@@ -91,11 +91,11 @@ protected String getManagementBaseUrl() {
 	}
 
 	protected String getManagementContextPath() {
-		return management.getBasePath();
+		return this.management.getBasePath();
 	}
 
 	protected String getServerContextPath() {
-		return servletContext.getContextPath();
+		return this.servletContext.getContextPath();
 	}
 
 	protected String getDispatcherServletPrefix() {