diff --git a/module/spring-boot-session/build.gradle b/module/spring-boot-session/build.gradle
index 10899e1965b..1ead82d474e 100644
--- a/module/spring-boot-session/build.gradle
+++ b/module/spring-boot-session/build.gradle
@@ -56,3 +56,7 @@ dependencies {
 
 	testRuntimeOnly("ch.qos.logback:logback-classic")
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}
diff --git a/module/spring-boot-session/src/test/java/org/springframework/boot/session/actuate/endpoint/SessionsEndpointTests.java b/module/spring-boot-session/src/test/java/org/springframework/boot/session/actuate/endpoint/SessionsEndpointTests.java
index 52fa95838bc..4f3335b0a24 100644
--- a/module/spring-boot-session/src/test/java/org/springframework/boot/session/actuate/endpoint/SessionsEndpointTests.java
+++ b/module/spring-boot-session/src/test/java/org/springframework/boot/session/actuate/endpoint/SessionsEndpointTests.java
@@ -55,7 +55,9 @@ class SessionsEndpointTests {
 	void sessionsForUsername() {
 		given(this.indexedSessionRepository.findByPrincipalName("user"))
 			.willReturn(Collections.singletonMap(session.getId(), session));
-		List<SessionDescriptor> result = this.endpoint.sessionsForUsername("user").getSessions();
+		SessionsDescriptor sessions = this.endpoint.sessionsForUsername("user");
+		assertThat(sessions).isNotNull();
+		List<SessionDescriptor> result = sessions.getSessions();
 		assertThat(result).hasSize(1);
 		assertThat(result.get(0).getId()).isEqualTo(session.getId());
 		assertThat(result.get(0).getAttributeNames()).isEqualTo(session.getAttributeNames());
@@ -76,6 +78,7 @@ class SessionsEndpointTests {
 	void getSession() {
 		given(this.sessionRepository.findById(session.getId())).willReturn(session);
 		SessionDescriptor result = this.endpoint.getSession(session.getId());
+		assertThat(result).isNotNull();
 		assertThat(result.getId()).isEqualTo(session.getId());
 		assertThat(result.getAttributeNames()).isEqualTo(session.getAttributeNames());
 		assertThat(result.getCreationTime()).isEqualTo(session.getCreationTime());
diff --git a/module/spring-boot-session/src/test/java/org/springframework/boot/session/autoconfigure/SessionAutoConfigurationTests.java b/module/spring-boot-session/src/test/java/org/springframework/boot/session/autoconfigure/SessionAutoConfigurationTests.java
index 91650bd17f8..341d4b7b0e0 100644
--- a/module/spring-boot-session/src/test/java/org/springframework/boot/session/autoconfigure/SessionAutoConfigurationTests.java
+++ b/module/spring-boot-session/src/test/java/org/springframework/boot/session/autoconfigure/SessionAutoConfigurationTests.java
@@ -19,6 +19,9 @@ package org.springframework.boot.session.autoconfigure;
 import java.util.Collections;
 
 import jakarta.servlet.DispatcherType;
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.ServletRequest;
+import jakarta.servlet.ServletResponse;
 import org.assertj.core.api.InstanceOfAssertFactories;
 import org.junit.jupiter.api.Test;
 import org.mockito.InOrder;
@@ -64,9 +67,11 @@ class SessionAutoConfigurationTests {
 		this.contextRunner.withUserConfiguration(SessionRepositoryConfiguration.class).run((context) -> {
 			AbstractFilterRegistrationBean<?> registration = context.getBean(AbstractFilterRegistrationBean.class);
 			DelegatingFilterProxy delegatingFilterProxy = (DelegatingFilterProxy) registration.getFilter();
+			assertThat(delegatingFilterProxy).isNotNull();
 			try {
 				// Trigger actual initialization
-				delegatingFilterProxy.doFilter(null, null, null);
+				delegatingFilterProxy.doFilter(mock(ServletRequest.class), mock(ServletResponse.class),
+						mock(FilterChain.class));
 			}
 			catch (Exception ex) {
 				// Ignore