diff --git a/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/autoconfigure/WebServicesAutoConfiguration.java b/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/autoconfigure/WebServicesAutoConfiguration.java
index e1694d926f5..beb56ff20a4 100644
--- a/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/autoconfigure/WebServicesAutoConfiguration.java
+++ b/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/autoconfigure/WebServicesAutoConfiguration.java
@@ -44,6 +44,7 @@ import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Role;
 import org.springframework.core.io.Resource;
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 import org.springframework.ws.config.annotation.EnableWs;
 import org.springframework.ws.config.annotation.WsConfigurationSupport;
@@ -96,6 +97,7 @@ public final class WebServicesAutoConfiguration {
 	static class WsdlDefinitionBeanFactoryPostProcessor
 			implements BeanDefinitionRegistryPostProcessor, ApplicationContextAware {
 
+		@SuppressWarnings("NullAway.Init")
 		private ApplicationContext applicationContext;
 
 		@Override
@@ -125,8 +127,9 @@ public final class WebServicesAutoConfiguration {
 				BeanDefinition beanDefinition = BeanDefinitionBuilder
 					.rootBeanDefinition(type, () -> beanSupplier.apply(resource))
 					.getBeanDefinition();
-				registry.registerBeanDefinition(StringUtils.stripFilenameExtension(resource.getFilename()),
-						beanDefinition);
+				String filename = resource.getFilename();
+				Assert.state(filename != null, "'filename' must not be null");
+				registry.registerBeanDefinition(StringUtils.stripFilenameExtension(filename), beanDefinition);
 			}
 		}
 
diff --git a/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/autoconfigure/client/package-info.java b/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/autoconfigure/client/package-info.java
index 886110ca10c..9b5ef745397 100644
--- a/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/autoconfigure/client/package-info.java
+++ b/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/autoconfigure/client/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Auto-configuration for Spring Web Services Clients.
  */
+@NullMarked
 package org.springframework.boot.webservices.autoconfigure.client;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/autoconfigure/package-info.java b/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/autoconfigure/package-info.java
index 344d4fd28cb..4be1bc2484e 100644
--- a/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/autoconfigure/package-info.java
+++ b/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/autoconfigure/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Auto-configuration for Spring Web Services.
  */
+@NullMarked
 package org.springframework.boot.webservices.autoconfigure;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/client/WebServiceMessageSenderFactory.java b/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/client/WebServiceMessageSenderFactory.java
index b915c695283..a1d9c836edc 100644
--- a/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/client/WebServiceMessageSenderFactory.java
+++ b/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/client/WebServiceMessageSenderFactory.java
@@ -16,6 +16,8 @@
 
 package org.springframework.boot.webservices.client;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
 import org.springframework.boot.http.client.ClientHttpRequestFactorySettings;
 import org.springframework.http.client.ClientHttpRequestFactory;
@@ -66,7 +68,7 @@ public interface WebServiceMessageSenderFactory {
 	 * @return a new {@link WebServiceMessageSenderFactory}
 	 */
 	static WebServiceMessageSenderFactory http(ClientHttpRequestFactoryBuilder<?> requestFactoryBuilder,
-			ClientHttpRequestFactorySettings requestFactorySettings) {
+			@Nullable ClientHttpRequestFactorySettings requestFactorySettings) {
 		Assert.notNull(requestFactoryBuilder, "'requestFactoryBuilder' must not be null");
 		return () -> new ClientHttpRequestMessageSender(requestFactoryBuilder.build(requestFactorySettings));
 	}
diff --git a/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/client/WebServiceTemplateBuilder.java b/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/client/WebServiceTemplateBuilder.java
index e5f110fdd9a..fb2f9886a56 100644
--- a/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/client/WebServiceTemplateBuilder.java
+++ b/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/client/WebServiceTemplateBuilder.java
@@ -25,6 +25,8 @@ import java.util.Set;
 
 import javax.xml.transform.TransformerFactory;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.BeanUtils;
 import org.springframework.boot.context.properties.PropertyMapper;
 import org.springframework.oxm.Marshaller;
@@ -56,27 +58,27 @@ import org.springframework.ws.transport.WebServiceMessageSender;
  */
 public class WebServiceTemplateBuilder {
 
-	private final WebServiceMessageSenderFactory httpMessageSenderFactory;
+	private final @Nullable WebServiceMessageSenderFactory httpMessageSenderFactory;
 
 	private final boolean detectHttpMessageSender;
 
-	private final Set<ClientInterceptor> interceptors;
+	private final @Nullable Set<ClientInterceptor> interceptors;
 
-	private final Set<WebServiceTemplateCustomizer> internalCustomizers;
+	private final @Nullable Set<WebServiceTemplateCustomizer> internalCustomizers;
 
 	private final Set<WebServiceTemplateCustomizer> customizers;
 
 	private final WebServiceMessageSenders messageSenders;
 
-	private final Marshaller marshaller;
+	private final @Nullable Marshaller marshaller;
 
-	private final Unmarshaller unmarshaller;
+	private final @Nullable Unmarshaller unmarshaller;
 
-	private final DestinationProvider destinationProvider;
+	private final @Nullable DestinationProvider destinationProvider;
 
-	private final Class<? extends TransformerFactory> transformerFactoryClass;
+	private final @Nullable Class<? extends TransformerFactory> transformerFactoryClass;
 
-	private final WebServiceMessageFactory messageFactory;
+	private final @Nullable WebServiceMessageFactory messageFactory;
 
 	public WebServiceTemplateBuilder(WebServiceTemplateCustomizer... customizers) {
 		this.httpMessageSenderFactory = null;
@@ -92,12 +94,14 @@ public class WebServiceTemplateBuilder {
 		this.messageFactory = null;
 	}
 
-	private WebServiceTemplateBuilder(WebServiceMessageSenderFactory messageSenderFactory,
-			boolean detectHttpMessageSender, Set<ClientInterceptor> interceptors,
-			Set<WebServiceTemplateCustomizer> internalCustomizers, Set<WebServiceTemplateCustomizer> customizers,
-			WebServiceMessageSenders messageSenders, Marshaller marshaller, Unmarshaller unmarshaller,
-			DestinationProvider destinationProvider, Class<? extends TransformerFactory> transformerFactoryClass,
-			WebServiceMessageFactory messageFactory) {
+	private WebServiceTemplateBuilder(@Nullable WebServiceMessageSenderFactory messageSenderFactory,
+			boolean detectHttpMessageSender, @Nullable Set<ClientInterceptor> interceptors,
+			@Nullable Set<WebServiceTemplateCustomizer> internalCustomizers,
+			Set<WebServiceTemplateCustomizer> customizers, WebServiceMessageSenders messageSenders,
+			@Nullable Marshaller marshaller, @Nullable Unmarshaller unmarshaller,
+			@Nullable DestinationProvider destinationProvider,
+			@Nullable Class<? extends TransformerFactory> transformerFactoryClass,
+			@Nullable WebServiceMessageFactory messageFactory) {
 		this.httpMessageSenderFactory = messageSenderFactory;
 		this.detectHttpMessageSender = detectHttpMessageSender;
 		this.interceptors = interceptors;
@@ -497,7 +501,7 @@ public class WebServiceTemplateBuilder {
 	}
 
 	private void applyCustomizers(WebServiceTemplate webServiceTemplate,
-			Set<WebServiceTemplateCustomizer> customizers) {
+			@Nullable Set<WebServiceTemplateCustomizer> customizers) {
 		if (!CollectionUtils.isEmpty(customizers)) {
 			for (WebServiceTemplateCustomizer customizer : customizers) {
 				customizer.customize(webServiceTemplate);
@@ -520,11 +524,11 @@ public class WebServiceTemplateBuilder {
 		}
 	}
 
-	private <T> Set<T> append(Set<T> set, T addition) {
+	private <T> Set<T> append(@Nullable Set<T> set, T addition) {
 		return append(set, Collections.singleton(addition));
 	}
 
-	private static <T> Set<T> append(Set<T> set, Collection<? extends T> additions) {
+	private static <T> Set<T> append(@Nullable Set<T> set, @Nullable Collection<? extends T> additions) {
 		Set<T> result = new LinkedHashSet<>((set != null) ? set : Collections.emptySet());
 		result.addAll((additions != null) ? additions : Collections.emptyList());
 		return Collections.unmodifiableSet(result);
diff --git a/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/client/package-info.java b/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/client/package-info.java
index 2da5647e9aa..b4a13e83930 100644
--- a/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/client/package-info.java
+++ b/module/spring-boot-webservices/src/main/java/org/springframework/boot/webservices/client/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Web Services client utilities.
  */
+@NullMarked
 package org.springframework.boot.webservices.client;
+
+import org.jspecify.annotations.NullMarked;