HHH-19515 incorporate feedback from @sebersole

Author: gavinking

hibernate-core/src/main/java/org/hibernate/jpa/HibernatePersistenceConfiguration.java

@@ -76,7 +76,7 @@
  * {@code hibernate-scan-jandex} or some other service implementing
  * {@link org.hibernate.boot.archive.scan.spi.ScannerFactory} is available,
  * the given URLs are scanned for entity classes, alleviating the program
- * of the need to call {@link #managedClass}.
+ * of the need to call {@link #managedClass} or {@link #mappingFile}.
  *
  * @apiNote The specification explicitly encourages implementors to extend
  *          {@link PersistenceConfiguration} to accommodate vendor-specific
@@ -90,7 +90,7 @@
  */
 public class HibernatePersistenceConfiguration extends PersistenceConfiguration {
 
-	private URL rootUrl;
+	private final URL rootUrl;
 	private final List<URL> jarFileUrls = new ArrayList<>();
 
 	/**
@@ -103,6 +103,7 @@ public class HibernatePersistenceConfiguration extends PersistenceConfiguration
 	 */
 	public HibernatePersistenceConfiguration(String name) {
 		super( name );
+		this.rootUrl = null;
 	}
 
 	/**