This problem is happening in GoAndClearFilter and FilterForm which are in wicket-extensions, but I'm testing the problem with wicket-phonebook which uses these classes.
When running wicket-phonebook with filters set, clearing the filters makes the list go back to the default, but the filter form controls are not reset to the default. Thus, to clear the filters and then refilter on different criteria, the user must manually delete the contents of the text fields and change the drop downs to blank.
Examining the code in GoAndClearFilter shows that originalState is being kept, which is used for refreshing the table. But I'm unclear on how to reset form filter values.