Common constant for DefaultBeanNameGenerator as well

Closes gh-22591

Author: jhoeller

spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanDefinitionReader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -61,7 +61,7 @@ public abstract class AbstractBeanDefinitionReader implements BeanDefinitionRead
 
 	private Environment environment;
 
-	private BeanNameGenerator beanNameGenerator = new DefaultBeanNameGenerator();
+	private BeanNameGenerator beanNameGenerator = DefaultBeanNameGenerator.INSTANCE;
 
 
 	/**
@@ -171,7 +171,7 @@ public Environment getEnvironment() {
 	 * <p>Default is a {@link DefaultBeanNameGenerator}.
 	 */
 	public void setBeanNameGenerator(@Nullable BeanNameGenerator beanNameGenerator) {
-		this.beanNameGenerator = (beanNameGenerator != null ? beanNameGenerator : new DefaultBeanNameGenerator());
+		this.beanNameGenerator = (beanNameGenerator != null ? beanNameGenerator : DefaultBeanNameGenerator.INSTANCE);
 	}
 
 	@Override

spring-beans/src/main/java/org/springframework/beans/factory/support/DefaultBeanNameGenerator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -27,6 +27,14 @@
  */
 public class DefaultBeanNameGenerator implements BeanNameGenerator {
 
+	/**
+	 * A convenient constant for a default {@code DefaultBeanNameGenerator} instance,
+	 * as used for {@link AbstractBeanDefinitionReader} setup.
+	 * @since 5.2
+	 */
+	public static final DefaultBeanNameGenerator INSTANCE = new DefaultBeanNameGenerator();
+
+
 	@Override
 	public String generateBeanName(BeanDefinition definition, BeanDefinitionRegistry registry) {
 		return BeanDefinitionReaderUtils.generateBeanName(definition, registry);