public function addRequirement($property, $requirement, $options = null)
{
if (!array_key_exists($property, $this->_docRequirements)) {
$this->_docRequirements[$property] = array();
}
$this->_docRequirements[$property][$requirement] = $options;
unset($this->_filters[$property]);
unset($this->_validators[$property]);
}