Make fields final

Closes gh-33537

buildSrc/src/main/java/org/springframework/boot/build/bom/bomr/UpgradeBom.java

@@ -58,7 +58,7 @@ import org.springframework.util.StringUtils;
  */
 public class UpgradeBom extends DefaultTask {
 
-	private Set<String> repositoryUrls;
+	private final Set<String> repositoryUrls;
 
 	private final BomExtension bom;
 

buildSrc/src/main/java/org/springframework/boot/build/mavenplugin/PrepareMavenBinaries.java

@@ -35,7 +35,7 @@ import org.gradle.api.tasks.TaskAction;
  */
 public class PrepareMavenBinaries extends DefaultTask {
 
-	private Set<String> versions = new LinkedHashSet<>();
+	private final Set<String> versions = new LinkedHashSet<>();
 
 	private File outputDir;
 

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/context/properties/ConfigurationPropertiesReportEndpointProperties.java

@@ -42,7 +42,7 @@ public class ConfigurationPropertiesReportEndpointProperties {
 	 * Roles used to determine whether a user is authorized to be shown unsanitized
 	 * values. When empty, all authenticated users are authorized.
 	 */
-	private Set<String> roles = new HashSet<>();
+	private final Set<String> roles = new HashSet<>();
 
 	public Show getShowValues() {
 		return this.showValues;

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/env/EnvironmentEndpointProperties.java

@@ -41,7 +41,7 @@ public class EnvironmentEndpointProperties {
 	 * Roles used to determine whether a user is authorized to be shown unsanitized
 	 * values. When empty, all authenticated users are authorized.
 	 */
-	private Set<String> roles = new HashSet<>();
+	private final Set<String> roles = new HashSet<>();
 
 	public Show getShowValues() {
 		return this.showValues;

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/quartz/QuartzEndpointProperties.java

@@ -41,7 +41,7 @@ public class QuartzEndpointProperties {
 	 * Roles used to determine whether a user is authorized to be shown unsanitized job or
 	 * trigger values. When empty, all authenticated users are authorized.
 	 */
-	private Set<String> roles = new HashSet<>();
+	private final Set<String> roles = new HashSet<>();
 
 	public Show getShowValues() {
 		return this.showValues;

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/availability/AvailabilityProbesAutoConfigurationTests.java

@@ -34,7 +34,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class AvailabilityProbesAutoConfigurationTests {
 
-	private ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
 			.withConfiguration(AutoConfigurations.of(ApplicationAvailabilityAutoConfiguration.class,
 					AvailabilityHealthContributorAutoConfiguration.class, AvailabilityProbesAutoConfiguration.class));
 

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/availability/AvailabilityProbesHealthEndpointGroupTests.java

@@ -32,7 +32,8 @@ import static org.mockito.Mockito.mock;
  */
 class AvailabilityProbesHealthEndpointGroupTests {
 
-	private AvailabilityProbesHealthEndpointGroup group = new AvailabilityProbesHealthEndpointGroup(null, "a", "b");
+	private final AvailabilityProbesHealthEndpointGroup group = new AvailabilityProbesHealthEndpointGroup(null, "a",
+			"b");
 
 	@Test
 	void isMemberWhenMemberReturnsTrue() {

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/availability/AvailabilityProbesHealthEndpointGroupsPostProcessorTests.java

@@ -37,7 +37,7 @@ import static org.mockito.Mockito.mock;
  */
 class AvailabilityProbesHealthEndpointGroupsPostProcessorTests {
 
-	private AvailabilityProbesHealthEndpointGroupsPostProcessor postProcessor = new AvailabilityProbesHealthEndpointGroupsPostProcessor(
+	private final AvailabilityProbesHealthEndpointGroupsPostProcessor postProcessor = new AvailabilityProbesHealthEndpointGroupsPostProcessor(
 			new MockEnvironment());
 
 	@Test

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/cloudfoundry/CloudFoundryEndpointFilterTests.java

@@ -31,7 +31,7 @@ import static org.mockito.Mockito.mock;
  */
 class CloudFoundryEndpointFilterTests {
 
-	private CloudFoundryEndpointFilter filter = new CloudFoundryEndpointFilter();
+	private final CloudFoundryEndpointFilter filter = new CloudFoundryEndpointFilter();
 
 	@Test
 	void matchIfDiscovererCloudFoundryShouldReturnFalse() {

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/cloudfoundry/reactive/CloudFoundryWebFluxEndpointIntegrationTests.java

@@ -71,9 +71,9 @@ import static org.mockito.Mockito.mock;
  */
 class CloudFoundryWebFluxEndpointIntegrationTests {
 
-	private static ReactiveTokenValidator tokenValidator = mock(ReactiveTokenValidator.class);
+	private static final ReactiveTokenValidator tokenValidator = mock(ReactiveTokenValidator.class);
 
-	private static ReactiveCloudFoundrySecurityService securityService = mock(
+	private static final ReactiveCloudFoundrySecurityService securityService = mock(
 			ReactiveCloudFoundrySecurityService.class);
 
 	private final ReactiveWebApplicationContextRunner contextRunner = new ReactiveWebApplicationContextRunner(

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/cloudfoundry/servlet/CloudFoundryMvcWebEndpointIntegrationTests.java

@@ -66,9 +66,9 @@ import static org.mockito.Mockito.mock;
  */
 class CloudFoundryMvcWebEndpointIntegrationTests {
 
-	private static TokenValidator tokenValidator = mock(TokenValidator.class);
+	private static final TokenValidator tokenValidator = mock(TokenValidator.class);
 
-	private static CloudFoundrySecurityService securityService = mock(CloudFoundrySecurityService.class);
+	private static final CloudFoundrySecurityService securityService = mock(CloudFoundrySecurityService.class);
 
 	@Test
 	void operationWithSecurityInterceptorForbidden() {

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/endpoint/jackson/JacksonEndpointAutoConfigurationTests.java

@@ -40,7 +40,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class JacksonEndpointAutoConfigurationTests {
 
-	private ApplicationContextRunner runner = new ApplicationContextRunner()
+	private final ApplicationContextRunner runner = new ApplicationContextRunner()
 			.withConfiguration(AutoConfigurations.of(JacksonEndpointAutoConfiguration.class));
 
 	@Test

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/MeterRegistryPostProcessorTests.java

@@ -50,11 +50,11 @@ class MeterRegistryPostProcessorTests {
 
 	private final MetricsProperties properties = new MetricsProperties();
 
-	private List<MeterRegistryCustomizer<?>> customizers = new ArrayList<>();
+	private final List<MeterRegistryCustomizer<?>> customizers = new ArrayList<>();
 
-	private List<MeterFilter> filters = new ArrayList<>();
+	private final List<MeterFilter> filters = new ArrayList<>();
 
-	private List<MeterBinder> binders = new ArrayList<>();
+	private final List<MeterBinder> binders = new ArrayList<>();
 
 	@Mock
 	private MeterRegistryCustomizer<MeterRegistry> mockCustomizer;

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/data/MetricsRepositoryMethodInvocationListenerBeanPostProcessorTests.java

@@ -36,9 +36,10 @@ import static org.mockito.Mockito.mock;
  */
 class MetricsRepositoryMethodInvocationListenerBeanPostProcessorTests {
 
-	private MetricsRepositoryMethodInvocationListener listener = mock(MetricsRepositoryMethodInvocationListener.class);
+	private final MetricsRepositoryMethodInvocationListener listener = mock(
+			MetricsRepositoryMethodInvocationListener.class);
 
-	private MetricsRepositoryMethodInvocationListenerBeanPostProcessor postProcessor = new MetricsRepositoryMethodInvocationListenerBeanPostProcessor(
+	private final MetricsRepositoryMethodInvocationListenerBeanPostProcessor postProcessor = new MetricsRepositoryMethodInvocationListenerBeanPostProcessor(
 			SingletonSupplier.of(this.listener));
 
 	@Test

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/observation/web/client/ClientHttpObservationConventionAdapterTests.java

@@ -44,12 +44,12 @@ class ClientHttpObservationConventionAdapterTests {
 
 	private static final String TEST_METRIC_NAME = "test.metric.name";
 
-	private ClientHttpObservationConventionAdapter convention = new ClientHttpObservationConventionAdapter(
+	private final ClientHttpObservationConventionAdapter convention = new ClientHttpObservationConventionAdapter(
 			TEST_METRIC_NAME, new DefaultRestTemplateExchangeTagsProvider());
 
-	private ClientHttpRequest request = new MockClientHttpRequest(HttpMethod.GET, URI.create("/resource/test"));
+	private final ClientHttpRequest request = new MockClientHttpRequest(HttpMethod.GET, URI.create("/resource/test"));
 
-	private ClientHttpResponse response = new MockClientHttpResponse("foo".getBytes(), HttpStatus.OK);
+	private final ClientHttpResponse response = new MockClientHttpResponse("foo".getBytes(), HttpStatus.OK);
 
 	private ClientRequestObservationContext context;
 

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/observation/web/client/ClientObservationConventionAdapterTests.java

@@ -43,13 +43,14 @@ class ClientObservationConventionAdapterTests {
 
 	private static final String TEST_METRIC_NAME = "test.metric.name";
 
-	private ClientObservationConventionAdapter convention = new ClientObservationConventionAdapter(TEST_METRIC_NAME,
-			new DefaultWebClientExchangeTagsProvider());
+	private final ClientObservationConventionAdapter convention = new ClientObservationConventionAdapter(
+			TEST_METRIC_NAME, new DefaultWebClientExchangeTagsProvider());
 
-	private ClientRequest.Builder requestBuilder = ClientRequest.create(HttpMethod.GET, URI.create("/resource/test"))
+	private final ClientRequest.Builder requestBuilder = ClientRequest
+			.create(HttpMethod.GET, URI.create("/resource/test"))
 			.attribute(WebClient.class.getName() + ".uriTemplate", "/resource/{name}");
 
-	private ClientResponse response = ClientResponse.create(HttpStatus.OK).body("foo").build();
+	private final ClientResponse response = ClientResponse.create(HttpStatus.OK).body("foo").build();
 
 	private ClientRequestObservationContext context;
 

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/observation/web/servlet/ServerRequestObservationConventionAdapterTests.java

@@ -47,14 +47,15 @@ class ServerRequestObservationConventionAdapterTests {
 
 	private static final String TEST_METRIC_NAME = "test.metric.name";
 
-	private ServerRequestObservationConventionAdapter convention = new ServerRequestObservationConventionAdapter(
+	private final ServerRequestObservationConventionAdapter convention = new ServerRequestObservationConventionAdapter(
 			TEST_METRIC_NAME, new DefaultWebMvcTagsProvider(), Collections.emptyList());
 
-	private MockHttpServletRequest request = new MockHttpServletRequest("GET", "/resource/test");
+	private final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/resource/test");
 
-	private MockHttpServletResponse response = new MockHttpServletResponse();
+	private final MockHttpServletResponse response = new MockHttpServletResponse();
 
-	private ServerRequestObservationContext context = new ServerRequestObservationContext(this.request, this.response);
+	private final ServerRequestObservationContext context = new ServerRequestObservationContext(this.request,
+			this.response);
 
 	@Test
 	void customNameIsUsed() {

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/web/servlet/CompositeHandlerExceptionResolverTests.java

@@ -43,9 +43,9 @@ class CompositeHandlerExceptionResolverTests {
 
 	private AnnotationConfigApplicationContext context;
 
-	private MockHttpServletRequest request = new MockHttpServletRequest();
+	private final MockHttpServletRequest request = new MockHttpServletRequest();
 
-	private MockHttpServletResponse response = new MockHttpServletResponse();
+	private final MockHttpServletResponse response = new MockHttpServletResponse();
 
 	@Test
 	void resolverShouldDelegateToOtherResolversInContext() {

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/annotation/EndpointDiscoverer.java

@@ -401,11 +401,11 @@ public abstract class EndpointDiscoverer<E extends ExposableEndpoint<O>, O exten
 
 		private final EndpointId id;
 
-		private boolean enabledByDefault;
+		private final boolean enabledByDefault;
 
 		private final Class<?> filter;
 
-		private Set<ExtensionBean> extensions = new LinkedHashSet<>();
+		private final Set<ExtensionBean> extensions = new LinkedHashSet<>();
 
 		EndpointBean(Environment environment, String beanName, Class<?> beanType, Supplier<Object> beanSupplier) {
 			MergedAnnotation<Endpoint> annotation = MergedAnnotations.from(beanType, SearchStrategy.TYPE_HIERARCHY)

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/health/Health.java

@@ -190,7 +190,7 @@ public final class Health extends HealthComponent {
 
 		private Status status;
 
-		private Map<String, Object> details;
+		private final Map<String, Object> details;
 
 		private Throwable exception;
 

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/logging/LoggersEndpoint.java

@@ -161,7 +161,7 @@ public class LoggersEndpoint {
 	 */
 	public static class LoggerLevelsDescriptor implements OperationResponseBody {
 
-		private String configuredLevel;
+		private final String configuredLevel;
 
 		public LoggerLevelsDescriptor(LogLevel configuredLevel) {
 			this.configuredLevel = getName(configuredLevel);
@@ -182,7 +182,7 @@ public class LoggersEndpoint {
 	 */
 	public static class GroupLoggerLevelsDescriptor extends LoggerLevelsDescriptor {
 
-		private List<String> members;
+		private final List<String> members;
 
 		public GroupLoggerLevelsDescriptor(LogLevel configuredLevel, List<String> members) {
 			super(configuredLevel);
@@ -200,7 +200,7 @@ public class LoggersEndpoint {
 	 */
 	public static class SingleLoggerLevelsDescriptor extends LoggerLevelsDescriptor {
 
-		private String effectiveLevel;
+		private final String effectiveLevel;
 
 		public SingleLoggerLevelsDescriptor(LoggerConfiguration configuration) {
 			super(configuration.getConfiguredLevel());

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/management/HeapDumpWebEndpoint.java

@@ -146,9 +146,9 @@ public class HeapDumpWebEndpoint {
 	 */
 	protected static class HotSpotDiagnosticMXBeanHeapDumper implements HeapDumper {
 
-		private Object diagnosticMXBean;
+		private final Object diagnosticMXBean;
 
-		private Method dumpHeapMethod;
+		private final Method dumpHeapMethod;
 
 		@SuppressWarnings("unchecked")
 		protected HotSpotDiagnosticMXBeanHeapDumper() {
@@ -189,9 +189,9 @@ public class HeapDumpWebEndpoint {
 	 */
 	private static final class OpenJ9DiagnosticsMXBeanHeapDumper implements HeapDumper {
 
-		private Object diagnosticMXBean;
+		private final Object diagnosticMXBean;
 
-		private Method dumpHeapMethod;
+		private final Method dumpHeapMethod;
 
 		@SuppressWarnings("unchecked")
 		private OpenJ9DiagnosticsMXBeanHeapDumper() {

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/export/prometheus/PrometheusPushGatewayManager.java

@@ -56,7 +56,7 @@ public class PrometheusPushGatewayManager {
 
 	private final TaskScheduler scheduler;
 
-	private ScheduledFuture<?> scheduled;
+	private final ScheduledFuture<?> scheduled;
 
 	/**
 	 * Create a new {@link PrometheusPushGatewayManager} instance using a single threaded

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/security/AuthenticationAuditListener.java

@@ -53,7 +53,7 @@ public class AuthenticationAuditListener extends AbstractAuthenticationAuditList
 
 	private static final String WEB_LISTENER_CHECK_CLASS = "org.springframework.security.web.authentication.switchuser.AuthenticationSwitchUserEvent";
 
-	private WebAuditListener webListener = maybeCreateWebListener();
+	private final WebAuditListener webListener = maybeCreateWebListener();
 
 	private static WebAuditListener maybeCreateWebListener() {
 		if (ClassUtils.isPresent(WEB_LISTENER_CHECK_CLASS, null)) {

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/context/properties/ConfigurationPropertiesReportEndpointSerializationTests.java

@@ -497,9 +497,9 @@ class ConfigurationPropertiesReportEndpointSerializationTests {
 
 	public static class InitializedMapAndListProperties extends Foo {
 
-		private Map<String, Boolean> map = new HashMap<>();
+		private final Map<String, Boolean> map = new HashMap<>();
 
-		private List<String> list = new ArrayList<>();
+		private final List<String> list = new ArrayList<>();
 
 		public Map<String, Boolean> getMap() {
 			return this.map;

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/context/properties/ConfigurationPropertiesReportEndpointTests.java

@@ -435,7 +435,7 @@ class ConfigurationPropertiesReportEndpointTests {
 
 		private Duration duration = Duration.ofSeconds(10);
 
-		private String ignored = "dummy";
+		private final String ignored = "dummy";
 
 		public String getDbPassword() {
 			return this.dbPassword;
@@ -803,7 +803,7 @@ class ConfigurationPropertiesReportEndpointTests {
 
 		private URI noPasswordUri = URI.create("http://user:@localhost:8080");
 
-		private List<String> simpleList = new ArrayList<>();
+		private final List<String> simpleList = new ArrayList<>();
 
 		private String rawSensitiveAddresses = "http://user:password@localhost:8080,http://user2:password2@localhost:8082";
 

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/invoke/reflect/OperationMethodParameterTests.java

@@ -38,16 +38,17 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class OperationMethodParameterTests {
 
-	private Method example = ReflectionUtils.findMethod(getClass(), "example", String.class, String.class);
+	private final Method example = ReflectionUtils.findMethod(getClass(), "example", String.class, String.class);
 
-	private Method exampleJsr305 = ReflectionUtils.findMethod(getClass(), "exampleJsr305", String.class, String.class);
-
-	private Method exampleMetaJsr305 = ReflectionUtils.findMethod(getClass(), "exampleMetaJsr305", String.class,
+	private final Method exampleJsr305 = ReflectionUtils.findMethod(getClass(), "exampleJsr305", String.class,
 			String.class);
 
-	private Method exampleJsr305NonNull = ReflectionUtils.findMethod(getClass(), "exampleJsr305NonNull", String.class,
+	private final Method exampleMetaJsr305 = ReflectionUtils.findMethod(getClass(), "exampleMetaJsr305", String.class,
 			String.class);
 
+	private final Method exampleJsr305NonNull = ReflectionUtils.findMethod(getClass(), "exampleJsr305NonNull",
+			String.class, String.class);
+
 	@Test
 	void getNameShouldReturnName() {
 		OperationMethodParameter parameter = new OperationMethodParameter("name", this.example.getParameters()[0]);

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/invoke/reflect/OperationMethodParametersTests.java

@@ -43,9 +43,9 @@ import static org.mockito.Mockito.mock;
  */
 class OperationMethodParametersTests {
 
-	private Method exampleMethod = ReflectionUtils.findMethod(getClass(), "example", String.class);
+	private final Method exampleMethod = ReflectionUtils.findMethod(getClass(), "example", String.class);
 
-	private Method exampleNoParamsMethod = ReflectionUtils.findMethod(getClass(), "exampleNoParams");
+	private final Method exampleNoParamsMethod = ReflectionUtils.findMethod(getClass(), "exampleNoParams");
 
 	@Test
 	void createWhenMethodIsNullShouldThrowException() {

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/invoke/reflect/OperationMethodTests.java

@@ -34,7 +34,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  */
 class OperationMethodTests {
 
-	private Method exampleMethod = ReflectionUtils.findMethod(getClass(), "example", String.class);
+	private final Method exampleMethod = ReflectionUtils.findMethod(getClass(), "example", String.class);
 
 	@Test
 	void createWhenMethodIsNullShouldThrowException() {

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/jmx/EndpointMBeanTests.java

@@ -54,9 +54,9 @@ class EndpointMBeanTests {
 
 	private static final String[] NO_SIGNATURE = {};
 
-	private TestExposableJmxEndpoint endpoint = new TestExposableJmxEndpoint(new TestJmxOperation());
+	private final TestExposableJmxEndpoint endpoint = new TestExposableJmxEndpoint(new TestJmxOperation());
 
-	private TestJmxOperationResponseMapper responseMapper = new TestJmxOperationResponseMapper();
+	private final TestJmxOperationResponseMapper responseMapper = new TestJmxOperationResponseMapper();
 
 	@Test
 	void createWhenResponseMapperIsNullShouldThrowException() {

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/jmx/JacksonJmxOperationResponseMapperTests.java

@@ -42,7 +42,7 @@ import static org.mockito.Mockito.spy;
  */
 class JacksonJmxOperationResponseMapperTests {
 
-	private JacksonJmxOperationResponseMapper mapper = new JacksonJmxOperationResponseMapper(null);
+	private final JacksonJmxOperationResponseMapper mapper = new JacksonJmxOperationResponseMapper(null);
 
 	private final BasicJsonTester json = new BasicJsonTester(getClass());
 

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/jmx/JmxEndpointExporterTests.java

@@ -61,9 +61,9 @@ class JmxEndpointExporterTests {
 	@Spy
 	private EndpointObjectNameFactory objectNameFactory = new TestEndpointObjectNameFactory();
 
-	private JmxOperationResponseMapper responseMapper = new TestJmxOperationResponseMapper();
+	private final JmxOperationResponseMapper responseMapper = new TestJmxOperationResponseMapper();
 
-	private List<ExposableJmxEndpoint> endpoints = new ArrayList<>();
+	private final List<ExposableJmxEndpoint> endpoints = new ArrayList<>();
 
 	@Captor
 	private ArgumentCaptor<Object> objectCaptor;

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/jmx/MBeanInfoFactoryTests.java

@@ -39,7 +39,7 @@ import static org.mockito.Mockito.mock;
  */
 class MBeanInfoFactoryTests {
 
-	private MBeanInfoFactory factory = new MBeanInfoFactory(new TestJmxOperationResponseMapper());
+	private final MBeanInfoFactory factory = new MBeanInfoFactory(new TestJmxOperationResponseMapper());
 
 	@Test
 	void getMBeanInfoShouldReturnMBeanInfo() {

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/web/annotation/RequestPredicateFactoryTests.java

@@ -42,7 +42,7 @@ class RequestPredicateFactoryTests {
 	private final RequestPredicateFactory factory = new RequestPredicateFactory(
 			new EndpointMediaTypes(Collections.emptyList(), Collections.emptyList()));
 
-	private String rootPath = "/root";
+	private final String rootPath = "/root";
 
 	@Test
 	void getRequestPredicateWhenHasMoreThanOneMatchAllThrowsException() {

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/health/AbstractHealthIndicatorTests.java

@@ -94,7 +94,7 @@ class AbstractHealthIndicatorTests {
 
 	static class TestHealthIndicator extends AbstractHealthIndicator {
 
-		private Consumer<Builder> action;
+		private final Consumer<Builder> action;
 
 		TestHealthIndicator(String message, Consumer<Builder> action) {
 			super(message);

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/management/HeapDumpWebEndpointWebIntegrationTests.java

@@ -83,7 +83,7 @@ class HeapDumpWebEndpointWebIntegrationTests {
 
 		private boolean available;
 
-		private String heapDump = "HEAPDUMP";
+		private final String heapDump = "HEAPDUMP";
 
 		private File file;
 

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/MetricsEndpointWebIntegrationTests.java

@@ -42,7 +42,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class MetricsEndpointWebIntegrationTests {
 
-	private static MeterRegistry registry = new SimpleMeterRegistry(SimpleConfig.DEFAULT, new MockClock());
+	private static final MeterRegistry registry = new SimpleMeterRegistry(SimpleConfig.DEFAULT, new MockClock());
 
 	private final ObjectMapper mapper = new ObjectMapper();
 

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/data/DefaultRepositoryTagsProviderTests.java

@@ -39,7 +39,7 @@ import static org.mockito.Mockito.mock;
  */
 class DefaultRepositoryTagsProviderTests {
 
-	private DefaultRepositoryTagsProvider provider = new DefaultRepositoryTagsProvider();
+	private final DefaultRepositoryTagsProvider provider = new DefaultRepositoryTagsProvider();
 
 	@Test
 	void repositoryTagsIncludesRepository() {

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/export/prometheus/PrometheusPushGatewayManagerTests.java

@@ -61,9 +61,9 @@ class PrometheusPushGatewayManagerTests {
 	@Mock
 	private TaskScheduler scheduler;
 
-	private Duration pushRate = Duration.ofSeconds(1);
+	private final Duration pushRate = Duration.ofSeconds(1);
 
-	private Map<String, String> groupingKey = Collections.singletonMap("foo", "bar");
+	private final Map<String, String> groupingKey = Collections.singletonMap("foo", "bar");
 
 	@Captor
 	private ArgumentCaptor<Runnable> task;

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/web/client/ObservationRestTemplateCustomizerTests.java

@@ -34,11 +34,11 @@ class ObservationRestTemplateCustomizerTests {
 
 	private static final String TEST_METRIC_NAME = "http.test.metric.name";
 
-	private ObservationRegistry observationRegistry = TestObservationRegistry.create();
+	private final ObservationRegistry observationRegistry = TestObservationRegistry.create();
 
-	private RestTemplate restTemplate = new RestTemplate();
+	private final RestTemplate restTemplate = new RestTemplate();
 
-	private ObservationRestTemplateCustomizer customizer = new ObservationRestTemplateCustomizer(
+	private final ObservationRestTemplateCustomizer customizer = new ObservationRestTemplateCustomizer(
 			this.observationRegistry, new DefaultClientRequestObservationConvention(TEST_METRIC_NAME));
 
 	@Test

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/web/reactive/client/DefaultWebClientExchangeTagsProviderTests.java

@@ -44,7 +44,7 @@ class DefaultWebClientExchangeTagsProviderTests {
 
 	private static final String URI_TEMPLATE_ATTRIBUTE = WebClient.class.getName() + ".uriTemplate";
 
-	private WebClientExchangeTagsProvider tagsProvider = new DefaultWebClientExchangeTagsProvider();
+	private final WebClientExchangeTagsProvider tagsProvider = new DefaultWebClientExchangeTagsProvider();
 
 	private ClientRequest request;
 

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/web/reactive/client/ObservationWebClientCustomizerTests.java

@@ -34,15 +34,15 @@ class ObservationWebClientCustomizerTests {
 
 	private static final String TEST_METRIC_NAME = "http.test.metric.name";
 
-	private TestObservationRegistry observationRegistry = TestObservationRegistry.create();
+	private final TestObservationRegistry observationRegistry = TestObservationRegistry.create();
 
-	private ClientRequestObservationConvention observationConvention = new DefaultClientRequestObservationConvention(
+	private final ClientRequestObservationConvention observationConvention = new DefaultClientRequestObservationConvention(
 			TEST_METRIC_NAME);
 
-	private ObservationWebClientCustomizer customizer = new ObservationWebClientCustomizer(this.observationRegistry,
-			this.observationConvention);
+	private final ObservationWebClientCustomizer customizer = new ObservationWebClientCustomizer(
+			this.observationRegistry, this.observationConvention);
 
-	private WebClient.Builder clientBuilder = WebClient.builder();
+	private final WebClient.Builder clientBuilder = WebClient.builder();
 
 	@Test
 	void shouldCustomizeObservationConfiguration() {

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/amqp/AbstractRabbitListenerContainerFactoryConfigurer.java

@@ -45,7 +45,7 @@ public abstract class AbstractRabbitListenerContainerFactoryConfigurer<T extends
 
 	private List<RabbitRetryTemplateCustomizer> retryTemplateCustomizers;
 
-	private RabbitProperties rabbitProperties;
+	private final RabbitProperties rabbitProperties;
 
 	/**
 	 * Creates a new configurer that will use the given {@code rabbitProperties}.

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/amqp/RabbitTemplateConfigurer.java

@@ -37,7 +37,7 @@ public class RabbitTemplateConfigurer {
 
 	private List<RabbitRetryTemplateCustomizer> retryTemplateCustomizers;
 
-	private RabbitProperties rabbitProperties;
+	private final RabbitProperties rabbitProperties;
 
 	/**
 	 * Creates a new configurer that will use the given {@code rabbitProperties}.

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/OnJndiCondition.java

@@ -81,7 +81,7 @@ class OnJndiCondition extends SpringBootCondition {
 
 	protected static class JndiLocator extends JndiLocatorSupport {
 
-		private String[] locations;
+		private final String[] locations;
 
 		public JndiLocator(String[] locations) {
 			this.locations = locations;

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/context/MessageSourceAutoConfiguration.java

@@ -87,7 +87,7 @@ public class MessageSourceAutoConfiguration {
 
 	protected static class ResourceBundleCondition extends SpringBootCondition {
 
-		private static ConcurrentReferenceHashMap<String, ConditionOutcome> cache = new ConcurrentReferenceHashMap<>();
+		private static final ConcurrentReferenceHashMap<String, ConditionOutcome> cache = new ConcurrentReferenceHashMap<>();
 
 		@Override
 		public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/graphql/servlet/GraphQlWebMvcAutoConfiguration.java

@@ -89,7 +89,7 @@ public class GraphQlWebMvcAutoConfiguration {
 	private static final Log logger = LogFactory.getLog(GraphQlWebMvcAutoConfiguration.class);
 
 	@SuppressWarnings("removal")
-	private static MediaType[] SUPPORTED_MEDIA_TYPES = new MediaType[] { MediaType.APPLICATION_GRAPHQL_RESPONSE,
+	private static final MediaType[] SUPPORTED_MEDIA_TYPES = new MediaType[] { MediaType.APPLICATION_GRAPHQL_RESPONSE,
 			MediaType.APPLICATION_JSON, MediaType.APPLICATION_GRAPHQL };
 
 	@Bean

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/ldap/embedded/EmbeddedLdapProperties.java

@@ -58,7 +58,7 @@ public class EmbeddedLdapProperties {
 	/**
 	 * Schema validation.
 	 */
-	private Validation validation = new Validation();
+	private final Validation validation = new Validation();
 
 	public int getPort() {
 		return this.port;

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/logging/ConditionEvaluationReportMessage.java

@@ -41,7 +41,7 @@ import org.springframework.util.StringUtils;
  */
 public class ConditionEvaluationReportMessage {
 
-	private StringBuilder message;
+	private final StringBuilder message;
 
 	public ConditionEvaluationReportMessage(ConditionEvaluationReport report) {
 		this(report, "CONDITIONS EVALUATION REPORT");

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mail/MailProperties.java

@@ -69,7 +69,7 @@ public class MailProperties {
 	/**
 	 * Additional JavaMail Session properties.
 	 */
-	private Map<String, String> properties = new HashMap<>();
+	private final Map<String, String> properties = new HashMap<>();
 
 	/**
 	 * Session JNDI name. When set, takes precedence over other Session settings.

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.java

@@ -80,7 +80,7 @@ class HibernateJpaConfiguration extends JpaBaseConfiguration {
 
 	private final HibernateDefaultDdlAutoProvider defaultDdlAutoProvider;
 
-	private DataSourcePoolMetadataProvider poolMetadataProvider;
+	private final DataSourcePoolMetadataProvider poolMetadataProvider;
 
 	private final List<HibernatePropertiesCustomizer> hibernatePropertiesCustomizers;
 

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/ServerProperties.java

@@ -1787,12 +1787,12 @@ public class ServerProperties {
 			/**
 			 * Socket options as defined in org.xnio.Options.
 			 */
-			private Map<String, String> socket = new LinkedHashMap<>();
+			private final Map<String, String> socket = new LinkedHashMap<>();
 
 			/**
 			 * Server options as defined in io.undertow.UndertowOptions.
 			 */
-			private Map<String, String> server = new LinkedHashMap<>();
+			private final Map<String, String> server = new LinkedHashMap<>();
 
 			public Map<String, String> getServer() {
 				return this.server;

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/error/DefaultErrorViewResolver.java

@@ -66,7 +66,7 @@ public class DefaultErrorViewResolver implements ErrorViewResolver, Ordered {
 		SERIES_VIEWS = Collections.unmodifiableMap(views);
 	}
 
-	private ApplicationContext applicationContext;
+	private final ApplicationContext applicationContext;
 
 	private final Resources resources;
 
@@ -145,7 +145,7 @@ public class DefaultErrorViewResolver implements ErrorViewResolver, Ordered {
 	 */
 	private static class HtmlResourceView implements View {
 
-		private Resource resource;
+		private final Resource resource;
 
 		HtmlResourceView(Resource resource) {
 			this.resource = resource;

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/AbstractDependsOnBeanFactoryPostProcessorTests.java

@@ -38,7 +38,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class AbstractDependsOnBeanFactoryPostProcessorTests {
 
-	private ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
 			.withUserConfiguration(FooBarConfiguration.class);
 
 	@Test

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/AutoConfigurationImportSelectorTests.java

@@ -56,7 +56,7 @@ class AutoConfigurationImportSelectorTests {
 
 	private final MockEnvironment environment = new MockEnvironment();
 
-	private List<AutoConfigurationImportFilter> filters = new ArrayList<>();
+	private final List<AutoConfigurationImportFilter> filters = new ArrayList<>();
 
 	@BeforeEach
 	void setup() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/condition/ConditionalOnBeanTests.java

@@ -488,7 +488,7 @@ class ConditionalOnBeanTests {
 	@TestAnnotation
 	static class ExampleBean {
 
-		private String value;
+		private final String value;
 
 		ExampleBean(String value) {
 			this.value = value;

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/condition/ConditionalOnJndiTests.java

@@ -51,7 +51,7 @@ class ConditionalOnJndiTests {
 
 	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner();
 
-	private MockableOnJndi condition = new MockableOnJndi();
+	private final MockableOnJndi condition = new MockableOnJndi();
 
 	@BeforeEach
 	void setupThreadContextClassLoader() {
@@ -149,7 +149,7 @@ class ConditionalOnJndiTests {
 
 	static class MockableOnJndi extends OnJndiCondition {
 
-		private boolean jndiAvailable = true;
+		private final boolean jndiAvailable = true;
 
 		private String foundLocation;
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/condition/ConditionalOnMissingBeanTests.java

@@ -741,7 +741,7 @@ class ConditionalOnMissingBeanTests {
 	@TestAnnotation
 	static class ExampleBean {
 
-		private String value;
+		private final String value;
 
 		ExampleBean(String value) {
 			this.value = value;

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/condition/ConditionalOnPropertyTests.java

@@ -50,7 +50,7 @@ class ConditionalOnPropertyTests {
 
 	private ConfigurableApplicationContext context;
 
-	private ConfigurableEnvironment environment = new StandardEnvironment();
+	private final ConfigurableEnvironment environment = new StandardEnvironment();
 
 	@AfterEach
 	void tearDown() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/condition/OnClassConditionAutoConfigurationImportFilterTests.java

@@ -35,9 +35,9 @@ import static org.mockito.Mockito.mock;
  */
 class OnClassConditionAutoConfigurationImportFilterTests {
 
-	private OnClassCondition filter = new OnClassCondition();
+	private final OnClassCondition filter = new OnClassCondition();
 
-	private DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
+	private final DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
 
 	@BeforeEach
 	void setup() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/data/neo4j/city/City.java

@@ -32,11 +32,11 @@ public class City implements Serializable {
 	@GeneratedValue
 	private Long id;
 
-	private String name;
+	private final String name;
 
 	private String state;
 
-	private Country country;
+	private final Country country;
 
 	private String map;
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/data/neo4j/country/Country.java

@@ -31,7 +31,7 @@ public class Country implements Serializable {
 	@GeneratedValue
 	private Long id;
 
-	private String name;
+	private final String name;
 
 	public Country(String name) {
 		this.name = name;

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/data/redis/RedisRepositoriesAutoConfigurationTests.java

@@ -50,7 +50,7 @@ class RedisRepositoriesAutoConfigurationTests {
 	public static RedisContainer redis = new RedisContainer().withStartupAttempts(5)
 			.withStartupTimeout(Duration.ofMinutes(10));
 
-	private AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+	private final AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
 
 	@BeforeEach
 	void setUp() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/graphql/GraphQlTestDataFetchers.java

@@ -31,7 +31,8 @@ import org.springframework.lang.Nullable;
  */
 public final class GraphQlTestDataFetchers {
 
-	private static List<Book> books = Arrays.asList(new Book("book-1", "GraphQL for beginners", 100, "John GraphQL"),
+	private static final List<Book> books = Arrays.asList(
+			new Book("book-1", "GraphQL for beginners", 100, "John GraphQL"),
 			new Book("book-2", "Harry Potter and the Philosopher's Stone", 223, "Joanne Rowling"),
 			new Book("book-3", "Moby Dick", 635, "Moby Dick"), new Book("book-3", "Moby Dick", 635, "Moby Dick"));
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/groovy/template/GroovyTemplateAutoConfigurationTests.java

@@ -55,7 +55,7 @@ class GroovyTemplateAutoConfigurationTests {
 
 	private final BuildOutput buildOutput = new BuildOutput(getClass());
 
-	private AnnotationConfigServletWebApplicationContext context = new AnnotationConfigServletWebApplicationContext();
+	private final AnnotationConfigServletWebApplicationContext context = new AnnotationConfigServletWebApplicationContext();
 
 	@BeforeEach
 	void setupContext() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/groovy/template/GroovyTemplateAvailabilityProviderTests.java

@@ -32,11 +32,11 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class GroovyTemplateAvailabilityProviderTests {
 
-	private TemplateAvailabilityProvider provider = new GroovyTemplateAvailabilityProvider();
+	private final TemplateAvailabilityProvider provider = new GroovyTemplateAvailabilityProvider();
 
-	private ResourceLoader resourceLoader = new DefaultResourceLoader();
+	private final ResourceLoader resourceLoader = new DefaultResourceLoader();
 
-	private MockEnvironment environment = new MockEnvironment();
+	private final MockEnvironment environment = new MockEnvironment();
 
 	@Test
 	void availabilityOfTemplateInDefaultLocation() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/gson/GsonAutoConfigurationTests.java

@@ -241,7 +241,7 @@ class GsonAutoConfigurationTests {
 		private Long data = 1L;
 
 		@SuppressWarnings("unused")
-		private String owner = null;
+		private final String owner = null;
 
 		public void setData(Long data) {
 			this.data = data;
@@ -254,7 +254,7 @@ class GsonAutoConfigurationTests {
 		@SuppressWarnings("unused")
 		class NestedObject {
 
-			private String data = "nested";
+			private final String data = "nested";
 
 		}
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jackson/JacksonAutoConfigurationTests.java

@@ -636,7 +636,7 @@ class JacksonAutoConfigurationTests {
 
 	static class CustomModule extends SimpleModule {
 
-		private Set<ObjectCodec> owners = new HashSet<>();
+		private final Set<ObjectCodec> owners = new HashSet<>();
 
 		@Override
 		public void setupModule(SetupContext context) {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jdbc/DataSourceJsonSerializationTests.java

@@ -80,7 +80,7 @@ class DataSourceJsonSerializationTests {
 
 	static class TomcatDataSourceSerializer extends JsonSerializer<DataSource> {
 
-		private ConversionService conversionService = new DefaultConversionService();
+		private final ConversionService conversionService = new DefaultConversionService();
 
 		@Override
 		public void serialize(DataSource value, JsonGenerator jgen, SerializerProvider provider) throws IOException {
@@ -99,7 +99,7 @@ class DataSourceJsonSerializationTests {
 
 	static class GenericSerializerModifier extends BeanSerializerModifier {
 
-		private ConversionService conversionService = new DefaultConversionService();
+		private final ConversionService conversionService = new DefaultConversionService();
 
 		@Override
 		public List<BeanPropertyWriter> changeProperties(SerializationConfig config, BeanDescription beanDesc,

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jmx/ParentAwareNamingStrategyTests.java

@@ -34,7 +34,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class ParentAwareNamingStrategyTests {
 
-	private ApplicationContextRunner contextRunner = new ApplicationContextRunner();
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner();
 
 	@Test
 	void objectNameMatchesManagedResourceByDefault() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/liquibase/LiquibaseAutoConfigurationTests.java

@@ -462,7 +462,7 @@ class LiquibaseAutoConfigurationTests {
 	@Configuration(proxyBeanMethods = false)
 	static class CustomDataSourceConfiguration {
 
-		private String name = UUID.randomUUID().toString();
+		private final String name = UUID.randomUUID().toString();
 
 		@Bean(destroyMethod = "shutdown")
 		EmbeddedDatabase dataSource() throws SQLException {
@@ -484,7 +484,7 @@ class LiquibaseAutoConfigurationTests {
 	@Configuration(proxyBeanMethods = false)
 	static class CustomDriverConfiguration {
 
-		private String name = UUID.randomUUID().toString();
+		private final String name = UUID.randomUUID().toString();
 
 		@Bean
 		SimpleDriverDataSource dataSource() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/logging/ConditionEvaluationReportLoggingListenerTests.java

@@ -51,7 +51,7 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 @ExtendWith(OutputCaptureExtension.class)
 class ConditionEvaluationReportLoggingListenerTests {
 
-	private ConditionEvaluationReportLoggingListener initializer = new ConditionEvaluationReportLoggingListener();
+	private final ConditionEvaluationReportLoggingListener initializer = new ConditionEvaluationReportLoggingListener();
 
 	@Test
 	void logsDebugOnContextRefresh(CapturedOutput output) {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/SecurityPropertiesTests.java

@@ -33,11 +33,11 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class SecurityPropertiesTests {
 
-	private SecurityProperties security = new SecurityProperties();
+	private final SecurityProperties security = new SecurityProperties();
 
 	private Binder binder;
 
-	private MapConfigurationPropertySource source = new MapConfigurationPropertySource();
+	private final MapConfigurationPropertySource source = new MapConfigurationPropertySource();
 
 	@BeforeEach
 	void setUp() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/oauth2/client/OAuth2ClientPropertiesTests.java

@@ -28,7 +28,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
  */
 class OAuth2ClientPropertiesTests {
 
-	private OAuth2ClientProperties properties = new OAuth2ClientProperties();
+	private final OAuth2ClientProperties properties = new OAuth2ClientProperties();
 
 	@Test
 	void clientIdAbsentThrowsException() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/oauth2/resource/servlet/OAuth2ResourceServerAutoConfigurationTests.java

@@ -79,7 +79,7 @@ import static org.mockito.Mockito.mock;
  */
 class OAuth2ResourceServerAutoConfigurationTests {
 
-	private WebApplicationContextRunner contextRunner = new WebApplicationContextRunner()
+	private final WebApplicationContextRunner contextRunner = new WebApplicationContextRunner()
 			.withConfiguration(AutoConfigurations.of(OAuth2ResourceServerAutoConfiguration.class))
 			.withUserConfiguration(TestConfig.class);
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/reactive/StaticResourceRequestTests.java

@@ -45,7 +45,7 @@ import static org.mockito.Mockito.mock;
  */
 class StaticResourceRequestTests {
 
-	private StaticResourceRequest resourceRequest = StaticResourceRequest.INSTANCE;
+	private final StaticResourceRequest resourceRequest = StaticResourceRequest.INSTANCE;
 
 	@Test
 	void atCommonLocationsShouldMatchCommonLocations() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/servlet/StaticResourceRequestTests.java

@@ -38,7 +38,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  */
 class StaticResourceRequestTests {
 
-	private StaticResourceRequest resourceRequest = StaticResourceRequest.INSTANCE;
+	private final StaticResourceRequest resourceRequest = StaticResourceRequest.INSTANCE;
 
 	@Test
 	void atCommonLocationsShouldMatchCommonLocations() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/sql/init/SqlInitializationAutoConfigurationTests.java

@@ -47,7 +47,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class SqlInitializationAutoConfigurationTests {
 
-	private ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
 			.withConfiguration(AutoConfigurations.of(SqlInitializationAutoConfiguration.class)).withPropertyValues(
 					"spring.datasource.generate-unique-name:true", "spring.r2dbc.generate-unique-name:true");
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/template/TemplateAvailabilityProvidersTests.java

@@ -49,11 +49,11 @@ class TemplateAvailabilityProvidersTests {
 	@Mock
 	private TemplateAvailabilityProvider provider;
 
-	private String view = "view";
+	private final String view = "view";
 
-	private ClassLoader classLoader = getClass().getClassLoader();
+	private final ClassLoader classLoader = getClass().getClassLoader();
 
-	private MockEnvironment environment = new MockEnvironment();
+	private final MockEnvironment environment = new MockEnvironment();
 
 	@Mock
 	private ResourceLoader resourceLoader;

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/validation/ValidationAutoConfigurationTests.java

@@ -422,7 +422,7 @@ class ValidationAutoConfigurationTests {
 
 		static class TestBeanPostProcessor implements BeanPostProcessor {
 
-			private Set<String> postProcessed = new HashSet<>();
+			private final Set<String> postProcessed = new HashSet<>();
 
 			@Override
 			public Object postProcessAfterInitialization(Object bean, String name) {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/validation/ValidatorAdapterTests.java

@@ -134,7 +134,7 @@ class ValidatorAdapterTests {
 	static class SampleData {
 
 		@Min(42)
-		private int counter;
+		private final int counter;
 
 		SampleData(int counter) {
 			this.counter = counter;

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/reactive/ReactiveWebServerFactoryCustomizerTests.java

@@ -39,7 +39,7 @@ import static org.mockito.Mockito.mock;
  */
 class ReactiveWebServerFactoryCustomizerTests {
 
-	private ServerProperties properties = new ServerProperties();
+	private final ServerProperties properties = new ServerProperties();
 
 	private ReactiveWebServerFactoryCustomizer customizer;
 

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/WelcomePageIntegrationTests.java

@@ -48,7 +48,7 @@ class WelcomePageIntegrationTests {
 	@LocalServerPort
 	private int port;
 
-	private TestRestTemplate template = new TestRestTemplate();
+	private final TestRestTemplate template = new TestRestTemplate();
 
 	@Test
 	void contentStrategyWithWelcomePage() throws Exception {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/error/DefaultErrorViewResolverTests.java

@@ -65,9 +65,9 @@ class DefaultErrorViewResolverTests {
 
 	private Resources resourcesProperties;
 
-	private Map<String, Object> model = new HashMap<>();
+	private final Map<String, Object> model = new HashMap<>();
 
-	private HttpServletRequest request = new MockHttpServletRequest();
+	private final HttpServletRequest request = new MockHttpServletRequest();
 
 	@BeforeEach
 	void setup() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/error/RemappedErrorViewIntegrationTests.java

@@ -51,7 +51,7 @@ class RemappedErrorViewIntegrationTests {
 	@LocalServerPort
 	private int port;
 
-	private TestRestTemplate template = new TestRestTemplate();
+	private final TestRestTemplate template = new TestRestTemplate();
 
 	@Test
 	void directAccessToErrorPage() {

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/websocket/servlet/WebSocketMessagingAutoConfigurationTests.java

@@ -78,7 +78,7 @@ import static org.junit.jupiter.api.Assertions.fail;
  */
 class WebSocketMessagingAutoConfigurationTests {
 
-	private AnnotationConfigServletWebServerApplicationContext context = new AnnotationConfigServletWebServerApplicationContext();
+	private final AnnotationConfigServletWebServerApplicationContext context = new AnnotationConfigServletWebServerApplicationContext();
 
 	private SockJsClient sockJsClient;
 
@@ -255,9 +255,9 @@ class WebSocketMessagingAutoConfigurationTests {
 
 	public static class Data {
 
-		private int foo;
+		private final int foo;
 
-		private String bar;
+		private final String bar;
 
 		Data(int foo, String bar) {
 			this.foo = foo;

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/autoconfigure/DevToolsProperties.java

@@ -35,9 +35,9 @@ import org.springframework.util.StringUtils;
 @ConfigurationProperties(prefix = "spring.devtools")
 public class DevToolsProperties {
 
-	private Restart restart = new Restart();
+	private final Restart restart = new Restart();
 
-	private Livereload livereload = new Livereload();
+	private final Livereload livereload = new Livereload();
 
 	@NestedConfigurationProperty
 	private final RemoteDevToolsProperties remote = new RemoteDevToolsProperties();

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/autoconfigure/RemoteDevToolsProperties.java

@@ -46,9 +46,9 @@ public class RemoteDevToolsProperties {
 	 */
 	private String secretHeaderName = DEFAULT_SECRET_HEADER_NAME;
 
-	private Restart restart = new Restart();
+	private final Restart restart = new Restart();
 
-	private Proxy proxy = new Proxy();
+	private final Proxy proxy = new Proxy();
 
 	public String getContextPath() {
 		return this.contextPath;

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/classpath/ClassPathFileSystemWatcher.java

@@ -39,7 +39,7 @@ public class ClassPathFileSystemWatcher implements InitializingBean, DisposableB
 
 	private final FileSystemWatcher fileSystemWatcher;
 
-	private ClassPathRestartStrategy restartStrategy;
+	private final ClassPathRestartStrategy restartStrategy;
 
 	private ApplicationContext applicationContext;
 

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/filewatch/DirectorySnapshot.java

@@ -43,7 +43,7 @@ class DirectorySnapshot {
 
 	private final Date time;
 
-	private Set<FileSnapshot> files;
+	private final Set<FileSnapshot> files;
 
 	/**
 	 * Create a new {@link DirectorySnapshot} for the given directory.

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/filewatch/FileSystemWatcher.java

@@ -237,7 +237,7 @@ public class FileSystemWatcher {
 
 		private Map<File, DirectorySnapshot> directories;
 
-		private SnapshotStateRepository snapshotStateRepository;
+		private final SnapshotStateRepository snapshotStateRepository;
 
 		private Watcher(AtomicInteger remainingScans, List<FileChangeListener> listeners, FileFilter triggerFilter,
 				long pollInterval, long quietPeriod, Map<File, DirectorySnapshot> directories,

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/remote/client/RemoteClientConfiguration.java

@@ -139,7 +139,7 @@ public class RemoteClientConfiguration implements InitializingBean {
 
 		private final String remoteUrl;
 
-		private ExecutorService executor = Executors.newSingleThreadExecutor();
+		private final ExecutorService executor = Executors.newSingleThreadExecutor();
 
 		LiveReloadConfiguration(DevToolsProperties properties, ClientHttpRequestFactory clientHttpRequestFactory,
 				@Value("${remoteUrl}") String remoteUrl) {

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/restart/Restarter.java

@@ -106,7 +106,7 @@ public class Restarter {
 
 	private boolean enabled = true;
 
-	private URL[] initialUrls;
+	private final URL[] initialUrls;
 
 	private final String mainClassName;
 

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/tunnel/client/HttpTunnelConnection.java

@@ -113,7 +113,7 @@ public class HttpTunnelConnection implements TunnelConnection {
 
 		private boolean open = true;
 
-		private AtomicLong requestSeq = new AtomicLong();
+		private final AtomicLong requestSeq = new AtomicLong();
 
 		public TunnelChannel(WritableByteChannel incomingChannel, Closeable closeable) {
 			this.forwarder = new HttpTunnelPayloadForwarder(incomingChannel);

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/tunnel/server/HttpTunnelServer.java

@@ -214,7 +214,7 @@ public class HttpTunnelServer {
 
 		private boolean closed;
 
-		private AtomicLong responseSeq = new AtomicLong();
+		private final AtomicLong responseSeq = new AtomicLong();
 
 		private long lastHttpRequestTime;
 
@@ -364,7 +364,7 @@ public class HttpTunnelServer {
 
 		private final ServerHttpResponse response;
 
-		private ServerHttpAsyncRequestControl async;
+		private final ServerHttpAsyncRequestControl async;
 
 		private volatile boolean complete = false;
 

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/tunnel/server/HttpTunnelServerHandler.java

@@ -31,7 +31,7 @@ import org.springframework.util.Assert;
  */
 public class HttpTunnelServerHandler implements Handler {
 
-	private HttpTunnelServer server;
+	private final HttpTunnelServer server;
 
 	/**
 	 * Create a new {@link HttpTunnelServerHandler} instance.

spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/classpath/ClassPathChangedEventTests.java

@@ -33,7 +33,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  */
 class ClassPathChangedEventTests {
 
-	private Object source = new Object();
+	private final Object source = new Object();
 
 	@Test
 	void changeSetMustNotBeNull() {

spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/classpath/ClassPathFileSystemWatcherTests.java

@@ -117,7 +117,7 @@ class ClassPathFileSystemWatcherTests {
 
 	static class Listener implements ApplicationListener<ClassPathChangedEvent> {
 
-		private List<ClassPathChangedEvent> events = new CopyOnWriteArrayList<>();
+		private final List<ClassPathChangedEvent> events = new CopyOnWriteArrayList<>();
 
 		@Override
 		public void onApplicationEvent(ClassPathChangedEvent event) {

spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/filewatch/FileSystemWatcherTests.java

@@ -50,7 +50,7 @@ class FileSystemWatcherTests {
 
 	private FileSystemWatcher watcher;
 
-	private List<Set<ChangedFiles>> changes = Collections.synchronizedList(new ArrayList<>());
+	private final List<Set<ChangedFiles>> changes = Collections.synchronizedList(new ArrayList<>());
 
 	@TempDir
 	File tempDir;

spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/remote/server/DispatcherTests.java

@@ -54,11 +54,11 @@ class DispatcherTests {
 	@Mock
 	private AccessManager accessManager;
 
-	private MockHttpServletResponse response = new MockHttpServletResponse();
+	private final MockHttpServletResponse response = new MockHttpServletResponse();
 
-	private ServerHttpRequest serverRequest = new ServletServerHttpRequest(new MockHttpServletRequest());
+	private final ServerHttpRequest serverRequest = new ServletServerHttpRequest(new MockHttpServletRequest());
 
-	private ServerHttpResponse serverResponse = new ServletServerHttpResponse(this.response);
+	private final ServerHttpResponse serverResponse = new ServletServerHttpResponse(this.response);
 
 	@Test
 	void accessManagerMustNotBeNull() {