$required = array_flip( [ 'title', 'tasks', 'signature', 'sigexpiry' ] );
$params = array_intersect_key( $this->getRequest()->getValues(), $required + $optional );
$missing = array_diff_key( $required, $params );
$required = array_flip( [ 'title', 'tasks', 'signature', 'sigexpiry' ] );
$params = array_intersect_key( $this->getRequest()->getValues(), $required + $optional );
$missing = array_diff_key( $required, $params );