Parameters are simply ignored. ResponseBuilder is supposed to convert a returned array to a DataTable so those filters apply but it doesn't.
This is important for piwik/piwik-mobile-2#3243
hideColumns filter work now for indexed arrays that have associative arrays
array(array('nb_visits' => 1, 'nb_hits' => 2), array('nb_visits' => 2, 'nb_hits' => 4))