diff --git a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/User.java b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/User.java
index c0e00e69576..2dc158101c6 100644
--- a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/User.java
+++ b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/User.java
@@ -21,6 +21,7 @@ import jakarta.persistence.Entity;
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.Id;
 import jakarta.persistence.Table;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.util.Assert;
 
@@ -35,11 +36,13 @@ public class User {
 
 	@Id
 	@GeneratedValue
-	private Long id;
+	private @Nullable Long id;
 
 	@Column(unique = true)
+	@SuppressWarnings("NullAway.Init")
 	private String username;
 
+	@SuppressWarnings("NullAway.Init")
 	private VehicleIdentificationNumber vin;
 
 	protected User() {
@@ -52,7 +55,7 @@ public class User {
 		this.vin = vin;
 	}
 
-	public Long getId() {
+	public @Nullable Long getId() {
 		return this.id;
 	}
 
diff --git a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/UserRepository.java b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/UserRepository.java
index 7e32e43c208..ebe4fcef113 100644
--- a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/UserRepository.java
+++ b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/UserRepository.java
@@ -16,6 +16,8 @@
 
 package smoketest.test.domain;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.data.repository.Repository;
 
 /**
@@ -25,6 +27,6 @@ import org.springframework.data.repository.Repository;
  */
 public interface UserRepository extends Repository<User, Long> {
 
-	User findByUsername(String username);
+	@Nullable User findByUsername(String username);
 
 }
diff --git a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/VehicleIdentificationNumber.java b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/VehicleIdentificationNumber.java
index bdc5a1e9b4b..d74a0d9d634 100644
--- a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/VehicleIdentificationNumber.java
+++ b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/VehicleIdentificationNumber.java
@@ -16,6 +16,8 @@
 
 package smoketest.test.domain;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.Assert;
 
 /**
@@ -34,7 +36,7 @@ public final class VehicleIdentificationNumber {
 	}
 
 	@Override
-	public boolean equals(Object obj) {
+	public boolean equals(@Nullable Object obj) {
 		if (obj == this) {
 			return true;
 		}
diff --git a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/package-info.java b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/domain/package-info.java
new file mode 100644
index 00000000000..25d56314721
--- /dev/null
+++ b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/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.test.domain;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/package-info.java b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/package-info.java
new file mode 100644
index 00000000000..377fd00ebc9
--- /dev/null
+++ b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/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.test;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/RemoteVehicleDetailsService.java b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/RemoteVehicleDetailsService.java
index 23c58264d31..7fb5bb87cd3 100644
--- a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/RemoteVehicleDetailsService.java
+++ b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/RemoteVehicleDetailsService.java
@@ -49,7 +49,10 @@ public class RemoteVehicleDetailsService implements VehicleDetailsService {
 		Assert.notNull(vin, "'vin' must not be null");
 		logger.debug("Retrieving vehicle data for: " + vin);
 		try {
-			return this.restTemplate.getForObject("/vehicle/{vin}/details", VehicleDetails.class, vin);
+			VehicleDetails response = this.restTemplate.getForObject("/vehicle/{vin}/details", VehicleDetails.class,
+					vin);
+			Assert.state(response != null, "'response' must not be null");
+			return response;
 		}
 		catch (HttpStatusCodeException ex) {
 			if (HttpStatus.NOT_FOUND.equals(ex.getStatusCode())) {
diff --git a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/VehicleDetails.java b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/VehicleDetails.java
index c2110303a73..8dab1672122 100644
--- a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/VehicleDetails.java
+++ b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/VehicleDetails.java
@@ -18,6 +18,7 @@ package smoketest.test.service;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.util.Assert;
 
@@ -49,7 +50,7 @@ public class VehicleDetails {
 	}
 
 	@Override
-	public boolean equals(Object obj) {
+	public boolean equals(@Nullable Object obj) {
 		if (obj == this) {
 			return true;
 		}
diff --git a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/VehicleIdentificationNumberNotFoundException.java b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/VehicleIdentificationNumberNotFoundException.java
index 20101701ae1..3f913eb141a 100644
--- a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/VehicleIdentificationNumberNotFoundException.java
+++ b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/VehicleIdentificationNumberNotFoundException.java
@@ -16,6 +16,7 @@
 
 package smoketest.test.service;
 
+import org.jspecify.annotations.Nullable;
 import smoketest.test.domain.VehicleIdentificationNumber;
 
 /**
@@ -31,7 +32,7 @@ public class VehicleIdentificationNumberNotFoundException extends RuntimeExcepti
 		this(vin, null);
 	}
 
-	public VehicleIdentificationNumberNotFoundException(VehicleIdentificationNumber vin, Throwable cause) {
+	public VehicleIdentificationNumberNotFoundException(VehicleIdentificationNumber vin, @Nullable Throwable cause) {
 		super("Unable to find VehicleIdentificationNumber " + vin, cause);
 		this.vehicleIdentificationNumber = vin;
 	}
diff --git a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/package-info.java b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/package-info.java
new file mode 100644
index 00000000000..4681269e45b
--- /dev/null
+++ b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/service/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.test.service;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/web/package-info.java b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/web/package-info.java
new file mode 100644
index 00000000000..91a0441959b
--- /dev/null
+++ b/smoke-test/spring-boot-smoke-test-test/src/main/java/smoketest/test/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.test.web;
+
+import org.jspecify.annotations.NullMarked;