diff --git a/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/domain/CustomerRepository.java b/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/domain/CustomerRepository.java
index 33edf56584e..abaaaf3b7a5 100644
--- a/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/domain/CustomerRepository.java
+++ b/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/domain/CustomerRepository.java
@@ -18,10 +18,12 @@ package smoketest.hateoas.domain;
 
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 public interface CustomerRepository {
 
 	List<Customer> findAll();
 
-	Customer findOne(Long id);
+	@Nullable Customer findOne(Long id);
 
 }
diff --git a/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/domain/InMemoryCustomerRepository.java b/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/domain/InMemoryCustomerRepository.java
index c08d38cbbc7..dd4d88883d4 100644
--- a/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/domain/InMemoryCustomerRepository.java
+++ b/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/domain/InMemoryCustomerRepository.java
@@ -19,6 +19,8 @@ package smoketest.hateoas.domain;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.stereotype.Repository;
 import org.springframework.util.ObjectUtils;
 
@@ -39,7 +41,7 @@ public class InMemoryCustomerRepository implements CustomerRepository {
 	}
 
 	@Override
-	public Customer findOne(Long id) {
+	public @Nullable Customer findOne(Long id) {
 		for (Customer customer : this.customers) {
 			if (ObjectUtils.nullSafeEquals(customer.getId(), id)) {
 				return customer;
diff --git a/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/domain/package-info.java b/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/domain/package-info.java
new file mode 100644
index 00000000000..56d4b3df095
--- /dev/null
+++ b/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/domain/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.hateoas.domain;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/package-info.java b/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/package-info.java
new file mode 100644
index 00000000000..4d987e60f67
--- /dev/null
+++ b/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/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.hateoas;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/web/CustomerController.java b/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/web/CustomerController.java
index 79f326dcfb0..df64c2ad3bf 100644
--- a/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/web/CustomerController.java
+++ b/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/web/CustomerController.java
@@ -55,7 +55,11 @@ public class CustomerController {
 
 	@GetMapping(path = "/{id}", produces = MediaType.APPLICATION_JSON_VALUE)
 	HttpEntity<EntityModel<Customer>> showCustomer(@PathVariable Long id) {
-		EntityModel<Customer> resource = EntityModel.of(this.repository.findOne(id));
+		Customer customer = this.repository.findOne(id);
+		if (customer == null) {
+			return ResponseEntity.notFound().build();
+		}
+		EntityModel<Customer> resource = EntityModel.of(customer);
 		resource.add(this.entityLinks.linkToItemResource(Customer.class, id));
 		return new ResponseEntity<>(resource, HttpStatus.OK);
 	}
diff --git a/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/web/package-info.java b/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/web/package-info.java
new file mode 100644
index 00000000000..e28548fd2d8
--- /dev/null
+++ b/smoke-test/spring-boot-smoke-test-hateoas/src/main/java/smoketest/hateoas/web/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.hateoas.web;
+
+import org.jspecify.annotations.NullMarked;