Polish "Add factory to create a NamedThreadLocal with an initial value"

See gh-24705

spring-beans/src/main/java/org/springframework/beans/factory/xml/XmlBeanDefinitionReader.java

@@ -136,13 +136,8 @@ public class XmlBeanDefinitionReader extends AbstractBeanDefinitionReader {
 
 	private final XmlValidationModeDetector validationModeDetector = new XmlValidationModeDetector();
 
-	private final ThreadLocal<Set<EncodedResource>> resourcesCurrentlyBeingLoaded =
-			new NamedThreadLocal<>("XML bean definition resources currently being loaded"){
-				@Override
-				protected Set<EncodedResource> initialValue() {
-					return new HashSet<>(4);
-				}
-			};
+	private final ThreadLocal<Set<EncodedResource>> resourcesCurrentlyBeingLoaded = NamedThreadLocal.withInitial(
+			"XML bean definition resources currently being loaded", () -> new HashSet<>(4));
 
 
 	/**

spring-context/src/main/java/org/springframework/context/support/SimpleThreadScope.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -55,7 +55,8 @@ public class SimpleThreadScope implements Scope {
 
 	private static final Log logger = LogFactory.getLog(SimpleThreadScope.class);
 
-	private final ThreadLocal<Map<String, Object>> threadScope = NamedThreadLocal.withInitial("SimpleThreadScope", HashMap::new);
+	private final ThreadLocal<Map<String, Object>> threadScope = NamedThreadLocal.withInitial(
+			"SimpleThreadScope", HashMap::new);
 
 	@Override
 	public Object get(String name, ObjectFactory<?> objectFactory) {

spring-core/src/main/java/org/springframework/core/NamedThreadLocal.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -48,12 +48,11 @@ public class NamedThreadLocal<T> extends ThreadLocal<T> {
 	/**
 	 * Creates a named thread local variable. The initial value of the variable is
 	 * determined by invoking the {@code get} method on the {@code Supplier}.
-	 *
 	 * @param <S> the type of the named thread local's value
+	 * @param name a descriptive name for the thread local
 	 * @param supplier the supplier to be used to determine the initial value
-	 * @return a new named thread local variable
-	 * @throws NullPointerException if the specified supplier is null
-	 * @since 5.2.5
+	 * @return a new named thread local
+	 * @since 6.1
 	 */
 	public static <S> ThreadLocal<S> withInitial(String name, Supplier<? extends S> supplier) {
 		return new SuppliedNamedThreadLocal<>(name, supplier);
@@ -83,6 +82,7 @@ public class NamedThreadLocal<T> extends ThreadLocal<T> {
 		protected T initialValue() {
 			return this.supplier.get();
 		}
+
 	}
 
 }