public function getColumns()
    {
        if (empty($this->_columns)) {
            $properties = $this->getInspector()->getClassProperties();
            foreach ($properties as $property) {
                $annotations = $this->getInspector()
                    ->getPropertyAnnotations($property);
                if ($annotations->hasAnnotation('column')) {
                    $this->_columns[$property] =
                        $annotations->getAnnotation('column');
                    $this->_columns[$property]->field = trim($property, '_');
                }
            }
        }
        return $this->_columns;
    }