add a comment to mark internal constructor called by quarkus

Signed-off-by: Gavin King <gavin@hibernate.org>

Author: gavinking

hibernate-core/src/main/java/org/hibernate/boot/internal/MetadataImpl.java

@@ -109,6 +109,7 @@ public class MetadataImpl implements MetadataImplementor, Serializable {
 	private final Map<String, SqmFunctionDescriptor> sqlFunctionMap;
 	private final Database database;
 
+	// note that this "internal" constructor is called by the Quarkus extension!
 	public MetadataImpl(
 			UUID uuid,
 			MetadataBuildingOptions metadataBuildingOptions,