feat: Spring Boot 4 support

.editorconfig

@@ -6,6 +6,9 @@ trim_trailing_whitespace = true
 
 [*.md]
 trim_trailing_whitespace = false
+max_line_length = 120
+ij_markdown_wrap_text_if_long = true
+ij_markdown_format_tables = true
 
 [*.java]
 indent_style = tab
@@ -23,7 +26,7 @@ ij_java_blank_lines_after_class_header = 0
 ij_java_doc_enable_formatting = false
 ij_java_class_count_to_use_import_on_demand = 100
 ij_java_names_count_to_use_import_on_demand = 100
-ij_java_imports_layout = |, java.**, |, jakarta.**, *, |, de.codecentric.boot.admin.**, |, $*
+ij_java_imports_layout = |, java.**, |, jakarta.**, *, tools.**, |, de.codecentric.boot.admin.**, |, $*
 ij_java_layout_static_imports_separately = true
 
 [*.xml]

.github/workflows/deploy-documentation.yml

@@ -4,11 +4,11 @@ on:
   workflow_dispatch:
     inputs:
       releaseversion:
-        description: 'Release version'
+        description: 'Version to publish the documentation for. This should be a tag that exists in the repository.'
+        type: string
         required: true
-        default: '3.0.0'
       copyDocsToCurrent:
-        description: "Should the docs be published at https://docs.spring-boot-admin.com? Otherwise they will be accessible by version number only."
+        description: "Mark docs as 'latest'? This will create a redirect from /current to the version being published. This should only be set for the latest version of the documentation."
         required: true
         type: boolean
         default: false

.github/workflows/release-to-maven-central.yml

@@ -4,11 +4,10 @@ on:
   workflow_dispatch:
     inputs:
       releaseversion:
-        description: 'Release version'
+        description: "Version to release and publish to maven central."
         required: true
-        default: '3.0.0'
       copyDocsToCurrent:
-        description: "Should the docs be published at https://docs.spring-boot-admin.com? Otherwise they will be accessible by version number only."
+        description: "Mark docs as 'latest'? This will create a redirect from /current to the version being published. This should only be set for the latest version of the documentation."
         required: true
         type: boolean
         default: false

.gitignore

@@ -28,3 +28,4 @@ node/
 
 .DS_Store
 mockServiceWorker.js
+/.github/agents/

pom.xml

@@ -30,7 +30,7 @@
     <url>https://github.com/codecentric/spring-boot-admin/</url>
 
     <properties>
-        <revision>3.5.8-SNAPSHOT</revision>
+        <revision>4.0.0-SNAPSHOT</revision>
 
         <java.version>17</java.version>
         <node.version>v22.12.0</node.version>
@@ -47,18 +47,17 @@
         <maven.site.skip>true</maven.site.skip>
 
         <!-- used dependencies versions -->
-        <spring-boot.version>3.5.10</spring-boot.version>
-        <spring-cloud.version>2025.0.0</spring-cloud.version>
+        <spring-boot.version>4.0.2</spring-boot.version>
+        <spring-cloud.version>2025.1.1</spring-cloud.version>
 
-        <jolokia-support-spring.version>2.4.3</jolokia-support-spring.version>
+        <jolokia-support-springboot.version>2.5.0</jolokia-support-springboot.version>
 
         <checkstyle.version>12.3.1</checkstyle.version>
         <findbugs-jsr305.version>3.0.2</findbugs-jsr305.version>
 
         <wiremock.version>3.13.2</wiremock.version>
         <hazelcast.version>5.6.0</hazelcast.version>
         <awaitility.version>4.3.0</awaitility.version>
-        <testcontainers.version>2.0.3</testcontainers.version>
         <jetty.version>12.1.6</jetty.version>
 
         <!-- plugin versions -->

spring-boot-admin-build/pom.xml

@@ -51,8 +51,8 @@
             </dependency>
             <dependency>
                 <groupId>org.jolokia</groupId>
-                <artifactId>jolokia-support-spring</artifactId>
-                <version>${jolokia-support-spring.version}</version>
+                <artifactId>jolokia-support-springboot</artifactId>
+                <version>${jolokia-support-springboot.version}</version>
             </dependency>
             <dependency>
                 <groupId>org.wiremock</groupId>
@@ -85,18 +85,6 @@
                 <version>${awaitility.version}</version>
                 <scope>test</scope>
             </dependency>
-            <dependency>
-                <groupId>org.testcontainers</groupId>
-                <artifactId>testcontainers</artifactId>
-                <version>${testcontainers.version}</version>
-                <scope>test</scope>
-            </dependency>
-            <dependency>
-                <groupId>org.testcontainers</groupId>
-                <artifactId>testcontainers-junit-jupiter</artifactId>
-                <version>${testcontainers.version}</version>
-                <scope>test</scope>
-            </dependency>
         </dependencies>
     </dependencyManagement>
 

spring-boot-admin-client/pom.xml

@@ -41,27 +41,27 @@
             <artifactId>spring-boot-starter-actuator</artifactId>
         </dependency>
         <dependency>
-            <groupId>org.springframework</groupId>
-            <artifactId>spring-web</artifactId>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-restclient</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-starter-web</artifactId>
+            <artifactId>spring-boot-starter-webflux</artifactId>
             <optional>true</optional>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-autoconfigure-processor</artifactId>
+            <artifactId>spring-boot-starter-webmvc</artifactId>
             <optional>true</optional>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
-            <artifactId>spring-boot-configuration-processor</artifactId>
+            <artifactId>spring-boot-autoconfigure-processor</artifactId>
             <optional>true</optional>
         </dependency>
         <dependency>
-            <groupId>org.springframework</groupId>
-            <artifactId>spring-webflux</artifactId>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-configuration-processor</artifactId>
             <optional>true</optional>
         </dependency>
         <dependency>
@@ -74,11 +74,6 @@
             <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>

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

@@ -19,11 +19,11 @@
 import java.time.Duration;
 import java.time.temporal.ChronoUnit;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.boot.cloud.CloudPlatform;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.convert.DurationUnit;
 import org.springframework.core.env.Environment;
-import org.springframework.lang.Nullable;
 
 @lombok.Data
 @ConfigurationProperties(prefix = "spring.boot.admin.client")
@@ -60,21 +60,18 @@ public class ClientProperties {
 	/**
 	 * Username for basic authentication on admin server
 	 */
-	@Nullable
-	private String username;
+	@Nullable private String username;
 
 	/**
 	 * Password for basic authentication on admin server
 	 */
-	@Nullable
-	private String password;
+	@Nullable private String password;
 
 	/**
 	 * Enable automatic deregistration on shutdown If not set it defaults to true if an
 	 * active {@link CloudPlatform} is present;
 	 */
-	@Nullable
-	private Boolean autoDeregistration = null;
+	@Nullable private Boolean autoDeregistration = null;
 
 	/**
 	 * Enable automatic registration when the application is ready.

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/CloudFoundryApplicationProperties.java

@@ -19,18 +19,16 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.boot.context.properties.ConfigurationProperties;
-import org.springframework.lang.Nullable;
 
 @lombok.Data
 @ConfigurationProperties("vcap.application")
 public class CloudFoundryApplicationProperties {
 
-	@Nullable
-	private String applicationId;
+	@Nullable private String applicationId;
 
-	@Nullable
-	private String instanceIndex;
+	@Nullable private String instanceIndex;
 
 	private List<String> uris = new ArrayList<>();
 

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

@@ -19,9 +19,9 @@
 import java.util.LinkedHashMap;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.boot.context.properties.ConfigurationProperties;
-import org.springframework.lang.Nullable;
 
 @lombok.Data
 @ConfigurationProperties(prefix = "spring.boot.admin.client.instance")
@@ -31,43 +31,37 @@ public class InstanceProperties {
 	 * Management-url to register with. Inferred at runtime, can be overridden in case the
 	 * reachable URL is different (e.g. Docker).
 	 */
-	@Nullable
-	private String managementUrl;
+	@Nullable private String managementUrl;
 
 	/**
 	 * Base url for computing the management-url to register with. The path is inferred at
 	 * runtime, and appended to the base url.
 	 */
-	@Nullable
-	private String managementBaseUrl;
+	@Nullable private String managementBaseUrl;
 
 	/**
 	 * Client-service-URL register with. Inferred at runtime, can be overridden in case
 	 * the reachable URL is different (e.g. Docker).
 	 */
-	@Nullable
-	private String serviceUrl;
+	@Nullable private String serviceUrl;
 
 	/**
 	 * Base url for computing the service-url to register with. The path is inferred at
 	 * runtime, and appended to the base url.
 	 */
-	@Nullable
-	private String serviceBaseUrl;
+	@Nullable private String serviceBaseUrl;
 
 	/**
 	 * Path for computing the service-url to register with. If not specified, defaults to
 	 * "/"
 	 */
-	@Nullable
-	private String servicePath;
+	@Nullable private String servicePath;
 
 	/**
 	 * Client-health-URL to register with. Inferred at runtime, can be overridden in case
 	 * the reachable URL is different (e.g. Docker). Must be unique all services registry.
 	 */
-	@Nullable
-	private String healthUrl;
+	@Nullable private String healthUrl;
 
 	/**
 	 * Name to register with. Defaults to ${spring.application.name}