This class was declared public because it was once believed that sub-classing it would be required to implement the "archive appending" feature. In that case, it were up to the archive driver implementation to select the right class.
This picture has changed, however. Selecting an archive entry collision strategy is now a matter of selecting the appropriate output preferences using TConfig.setOutputPreferences(...).
Hence, this class is not required to be public anymore. To the contrary, declaring it package private enables to do some required refactorings, hence this change.