Use lambda expressions for lazy instantiation (#1911)

Issue: SPR-17074

spring-context-support/src/main/java/org/springframework/cache/jcache/interceptor/DefaultJCacheOperationSource.java

@@ -172,7 +172,7 @@ public class DefaultJCacheOperationSource extends AnnotationJCacheOperationSourc
 
 	@Override
 	protected <T> T getBean(Class<T> type) {
-		Assert.state(this.beanFactory != null, "BeanFactory required for resolution of [" + type + "]");
+		Assert.state(this.beanFactory != null, () -> "BeanFactory required for resolution of [" + type + "]");
 		try {
 			return this.beanFactory.getBean(type);
 		}

spring-context/src/main/java/org/springframework/cache/support/NoOpCacheManager.java

@@ -55,7 +55,7 @@ public class NoOpCacheManager implements CacheManager {
 	public Cache getCache(String name) {
 		Cache cache = this.caches.get(name);
 		if (cache == null) {
-			this.caches.putIfAbsent(name, new NoOpCache(name));
+			this.caches.computeIfAbsent(name, key -> new NoOpCache(name));
 			synchronized (this.cacheNames) {
 				this.cacheNames.add(name);
 			}

spring-test/src/main/java/org/springframework/test/web/servlet/DefaultMvcResult.java

@@ -147,7 +147,7 @@ class DefaultMvcResult implements MvcResult {
 					" was not set during the specified timeToWait=" + timeToWait);
 		}
 		Object result = this.asyncResult.get();
-		Assert.state(result != RESULT_NONE, "Async result for handler [" + this.handler + "] was not set");
+		Assert.state(result != RESULT_NONE, () -> "Async result for handler [" + this.handler + "] was not set");
 		return this.asyncResult.get();
 	}
 

spring-web/src/main/java/org/springframework/web/server/ServerWebExchange.java

@@ -90,7 +90,7 @@ public interface ServerWebExchange {
 	@SuppressWarnings("unchecked")
 	default <T> T getRequiredAttribute(String name) {
 		T value = getAttribute(name);
-		Assert.notNull(value, "Required attribute '" + name + "' is missing.");
+		Assert.notNull(value, () -> "Required attribute '" + name + "' is missing.");
 		return value;
 	}
 

spring-web/src/main/java/org/springframework/web/server/WebSession.java

@@ -71,7 +71,7 @@ public interface WebSession {
 	@SuppressWarnings("unchecked")
 	default <T> T getRequiredAttribute(String name) {
 		T value = getAttribute(name);
-		Assert.notNull(value, "Required attribute '" + name + "' is missing.");
+		Assert.notNull(value, () -> "Required attribute '" + name + "' is missing.");
 		return value;
 	}
 

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/ExchangeFilterFunctions.java

@@ -94,7 +94,7 @@ public abstract class ExchangeFilterFunctions {
 		return ExchangeFilterFunction.ofRequestProcessor(request ->
 				credentialsFunction.apply(request)
 						.map(credentials -> Mono.just(insertAuthorizationHeader(request, credentials)))
-						.orElse(Mono.just(request)));
+						.orElseGet(() -> Mono.just(request)));
 	}
 
 	private static void checkIllegalCharacters(String username, String password) {

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/ModelInitializer.java

@@ -139,7 +139,7 @@ class ModelInitializer {
 				.ofNullable(AnnotatedElementUtils.findMergedAnnotation(param.getAnnotatedElement(), ModelAttribute.class))
 				.filter(ann -> StringUtils.hasText(ann.value()))
 				.map(ModelAttribute::value)
-				.orElse(Conventions.getVariableNameForParameter(param));
+				.orElseGet(() -> Conventions.getVariableNameForParameter(param));
 	}
 
 	/** Find {@code @ModelAttribute} arguments also listed as {@code @SessionAttributes}. */

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/RedirectView.java

@@ -244,7 +244,7 @@ public class RedirectView extends AbstractUrlBasedView {
 		while (found) {
 			String name = matcher.group(1);
 			Object value = (model.containsKey(name) ? model.get(name) : uriVariables.get(name));
-			Assert.notNull(value, "No value for URI variable '" + name + "'");
+			Assert.notNull(value, () -> "No value for URI variable '" + name + "'");
 			result.append(targetUrl.substring(endLastMatch, matcher.start()));
 			result.append(encodeUriVariable(value.toString()));
 			endLastMatch = matcher.end();

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/ViewResolutionResultHandler.java

@@ -286,7 +286,7 @@ public class ViewResolutionResultHandler extends HandlerResultHandlerSupport
 		return Optional.ofNullable(returnType.getMethodAnnotation(ModelAttribute.class))
 				.filter(ann -> StringUtils.hasText(ann.value()))
 				.map(ModelAttribute::value)
-				.orElse(Conventions.getVariableNameForParameter(returnType));
+				.orElseGet(() -> Conventions.getVariableNameForParameter(returnType));
 	}
 
 	private void updateBindingContext(BindingContext context, ServerWebExchange exchange) {

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ReactiveTypeHandler.java

@@ -120,7 +120,7 @@ class ReactiveTypeHandler {
 
 		Assert.notNull(returnValue, "Expected return value");
 		ReactiveAdapter adapter = this.reactiveRegistry.getAdapter(returnValue.getClass());
-		Assert.state(adapter != null, "Unexpected return value: " + returnValue);
+		Assert.state(adapter != null, () -> "Unexpected return value: " + returnValue);
 
 		ResolvableType elementType = ResolvableType.forMethodParameter(returnType).getGeneric();
 		Class<?> elementClass = elementType.toClass();

spring-websocket/src/main/java/org/springframework/web/socket/config/MessageBrokerBeanDefinitionParser.java

@@ -159,7 +159,7 @@ class MessageBrokerBeanDefinitionParser implements BeanDefinitionParser {
 			List<String> paths = Arrays.asList(StringUtils.tokenizeToStringArray(pathAttribute, ","));
 			for (String path : paths) {
 				path = path.trim();
-				Assert.state(StringUtils.hasText(path), "Invalid <stomp-endpoint> path attribute: " + pathAttribute);
+				Assert.state(StringUtils.hasText(path), () -> "Invalid <stomp-endpoint> path attribute: " + pathAttribute);
 				if (DomUtils.getChildElementByTagName(endpointElem, "sockjs") != null) {
 					path = path.endsWith("/") ? path + "**" : path + "/**";
 				}