diff --git a/smoke-test/spring-boot-smoke-test-actuator-extension/src/main/java/smoketest/actuator/extension/MyExtensionEndpointExposureOutcomeContributor.java b/smoke-test/spring-boot-smoke-test-actuator-extension/src/main/java/smoketest/actuator/extension/MyExtensionEndpointExposureOutcomeContributor.java
index e4516034aa1..0508c929f91 100644
--- a/smoke-test/spring-boot-smoke-test-actuator-extension/src/main/java/smoketest/actuator/extension/MyExtensionEndpointExposureOutcomeContributor.java
+++ b/smoke-test/spring-boot-smoke-test-actuator-extension/src/main/java/smoketest/actuator/extension/MyExtensionEndpointExposureOutcomeContributor.java
@@ -18,6 +18,8 @@ package smoketest.actuator.extension;
 
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.actuate.autoconfigure.endpoint.condition.EndpointExposureOutcomeContributor;
 import org.springframework.boot.actuate.autoconfigure.endpoint.expose.EndpointExposure;
 import org.springframework.boot.actuate.endpoint.EndpointId;
@@ -34,7 +36,7 @@ class MyExtensionEndpointExposureOutcomeContributor implements EndpointExposureO
 	}
 
 	@Override
-	public ConditionOutcome getExposureOutcome(EndpointId endpointId, Set<EndpointExposure> exposures,
+	public @Nullable ConditionOutcome getExposureOutcome(EndpointId endpointId, Set<EndpointExposure> exposures,
 			Builder message) {
 		if (exposures.contains(EndpointExposure.WEB) && this.filter.match(endpointId)) {
 			return ConditionOutcome.match(message.because("marked as exposed by a my extension '"
diff --git a/smoke-test/spring-boot-smoke-test-actuator-extension/src/main/java/smoketest/actuator/extension/MyExtensionWebMvcEndpointHandlerMapping.java b/smoke-test/spring-boot-smoke-test-actuator-extension/src/main/java/smoketest/actuator/extension/MyExtensionWebMvcEndpointHandlerMapping.java
index 63f6f6167c2..abc22a9715f 100644
--- a/smoke-test/spring-boot-smoke-test-actuator-extension/src/main/java/smoketest/actuator/extension/MyExtensionWebMvcEndpointHandlerMapping.java
+++ b/smoke-test/spring-boot-smoke-test-actuator-extension/src/main/java/smoketest/actuator/extension/MyExtensionWebMvcEndpointHandlerMapping.java
@@ -23,6 +23,7 @@ import java.util.Map;
 
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.actuate.endpoint.web.EndpointLinksResolver;
 import org.springframework.boot.actuate.endpoint.web.EndpointMapping;
@@ -40,7 +41,7 @@ class MyExtensionWebMvcEndpointHandlerMapping extends AbstractWebMvcEndpointHand
 	private final EndpointLinksResolver linksResolver;
 
 	MyExtensionWebMvcEndpointHandlerMapping(Collection<ExposableWebEndpoint> endpoints,
-			EndpointMediaTypes endpointMediaTypes, CorsConfiguration corsConfiguration) {
+			EndpointMediaTypes endpointMediaTypes, @Nullable CorsConfiguration corsConfiguration) {
 		super(new EndpointMapping(PATH), endpoints, endpointMediaTypes, corsConfiguration, true);
 		this.linksResolver = new EndpointLinksResolver(endpoints, PATH);
 		setOrder(-100);
diff --git a/smoke-test/spring-boot-smoke-test-actuator-extension/src/main/java/smoketest/actuator/extension/package-info.java b/smoke-test/spring-boot-smoke-test-actuator-extension/src/main/java/smoketest/actuator/extension/package-info.java
new file mode 100644
index 00000000000..bf66d10f89e
--- /dev/null
+++ b/smoke-test/spring-boot-smoke-test-actuator-extension/src/main/java/smoketest/actuator/extension/package-info.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+@NullMarked
+package smoketest.actuator.extension;
+
+import org.jspecify.annotations.NullMarked;