If you export a package of custom classes, remove the custom classes and import the exported package of custom classes ... the names of the classes and attributes are corrupt, blank or 'always-available'.

Steps to reproduce

1) export a package of custom classes
2) remove the custom classes
3) import the exported package of custom classes
4) review the names of the imported custom classes
5) notice the class name and class attribute names are corrupt, blank or 'always-available'.