Component: Zend\Validator\Callback

This is the inputFilter:

$this->add($factory->createInput(array(
    'name'       => 'username',
    'required'   => true,
    'filters'    => array(
        array(
            'name'    => 'StripTags',
        ),
    ),
    'validators' => array(
        array(
            'name'              => 'Callback',
            'options'           => array(
                'callback'      => array($model, 'userNameAvilable'),
            'callbackOptions'   => array('value I need'),
                'messages'   => array(
                    'callbackValue'  => "This username is already taken",
                ),
            ),
        ),
    ),
)));

If I dump Zend\Validator\Callback at Line 144 var_dump(array_merge($args, $options)); die();

I get

array(3) {
  [0]=>
  string(17) "invented_username"
  [1]=>
  array(7) {
    ["username"]=>
    string(17) "invented_username"
    ["password"]=>
    string(0) ""
    ["email"]=>
    string(0) ""
    ["fname"]=>
    string(0) ""
    ["lname"]=>
    string(0) ""
    ["role"]=>
    string(7) "student"
    ["Send"]=>
    string(4) "Send"
  }
  [2]=>
  string(12) "value I need"
}