Make DynamicPropertyRegistrarBeanInitializer public

In order to allow third parties (for example, Spring Boot) to ensure
that a DynamicPropertyRegistrarBeanInitializer has been registered in
an ApplicationContext which has not been customized by the
DynamicPropertiesContextCustomizer, this commit converts
DynamicPropertyRegistrarBeanInitializer to a public API for use in such
special use cases.

Closes gh-33593

spring-test/src/main/java/org/springframework/test/context/support/DynamicPropertiesContextCustomizer.java

@@ -50,10 +50,6 @@
  */
 class DynamicPropertiesContextCustomizer implements ContextCustomizer {
 
-	private static final String DYNAMIC_PROPERTY_REGISTRAR_BEAN_INITIALIZER_BEAN_NAME =
-			DynamicPropertiesContextCustomizer.class.getName() + ".dynamicPropertyRegistrarBeanInitializer";
-
-
 	private final Set<Method> methods;
 
 
@@ -70,11 +66,10 @@ public void customizeContext(ConfigurableApplicationContext context, MergedConte
 			throw new IllegalStateException("BeanFactory must be a BeanDefinitionRegistry");
 		}
 
-		if (!beanDefinitionRegistry.containsBeanDefinition(DYNAMIC_PROPERTY_REGISTRAR_BEAN_INITIALIZER_BEAN_NAME)) {
+		if (!beanDefinitionRegistry.containsBeanDefinition(DynamicPropertyRegistrarBeanInitializer.BEAN_NAME)) {
 			BeanDefinition beanDefinition = new RootBeanDefinition(DynamicPropertyRegistrarBeanInitializer.class);
 			beanDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
-			beanDefinitionRegistry.registerBeanDefinition(
-					DYNAMIC_PROPERTY_REGISTRAR_BEAN_INITIALIZER_BEAN_NAME, beanDefinition);
+			beanDefinitionRegistry.registerBeanDefinition(DynamicPropertyRegistrarBeanInitializer.BEAN_NAME, beanDefinition);
 		}
 
 		if (!this.methods.isEmpty()) {

spring-test/src/main/java/org/springframework/test/context/support/DynamicPropertyRegistrarBeanInitializer.java

@@ -30,16 +30,24 @@
 import org.springframework.test.context.DynamicPropertyRegistry;
 
 /**
- * Internal component which eagerly initializes {@link DynamicPropertyRegistrar}
+ * {@link BeanFactoryInitializer} that eagerly initializes {@link DynamicPropertyRegistrar}
  * beans.
  *
+ * <p>Primarily intended for internal use within the Spring TestContext Framework.
+ *
  * @author Sam Brannen
  * @since 6.2
  */
-class DynamicPropertyRegistrarBeanInitializer implements BeanFactoryInitializer<ListableBeanFactory>, EnvironmentAware {
+public class DynamicPropertyRegistrarBeanInitializer implements BeanFactoryInitializer<ListableBeanFactory>, EnvironmentAware {
 
 	private static final Log logger = LogFactory.getLog(DynamicPropertyRegistrarBeanInitializer.class);
 
+	/**
+	 * The bean name of the internally managed {@code DynamicPropertyRegistrarBeanInitializer}.
+	 */
+	static final String BEAN_NAME =
+			"org.springframework.test.context.support.internalDynamicPropertyRegistrarBeanInitializer";
+
 
 	@Nullable
 	private ConfigurableEnvironment environment;