public function getCleanUpColumns()
    {

        // load the colums that has to be cleaned-up
        $cleanUpColumns = $this->getConfiguration()->getParam(ConfigurationKeys::CLEAN_UP_EMPTY_COLUMNS);

        // query whether or not the image columns has to be cleaned-up also
        if ($this->getConfiguration()->hasParam(ConfigurationKeys::CLEAN_UP_EMPTY_IMAGE_COLUMNS) &&
            $this->getConfiguration()->hasParam(ConfigurationKeys::CLEAN_UP_EMPTY_IMAGE_COLUMNS, false)
        ) {
            // if yes load the image column names
            $imageTypes = array_keys($this->getImageTypes());

            // and append them to the column names from the configuration
            foreach ($imageTypes as $imageAttribute) {
                $cleanUpColumns[] = $imageAttribute;
            }
        }

        // return the array with the column names that has to be cleaned-up
        return $cleanUpColumns;
    }