_getPortableTableColumnDefinition() protected method

protected _getPortableTableColumnDefinition ( $tableColumn )
 protected function _getPortableTableColumnDefinition($tableColumn)
 {
     $columnDefinition = parent::_getPortableTableColumnDefinition($tableColumn);
     if ($columnDefinition->getNotnull() === true && empty($columnDefinition->getDefault())) {
         $columnDefinition->setDefault(null);
     }
     return $columnDefinition;
 }