/**
  * Returns a data class that is a DataObject type that this GridField should look like.
  *
  * @return string
  *
  * @throws LogicException
  */
 public function getModelClass()
 {
     if ($this->modelClassName) {
         return $this->modelClassName;
     }
     if ($this->list && $this->list->hasMethod('dataClass')) {
         $class = $this->list->dataClass();
         if ($class) {
             return $class;
         }
     }
     throw new LogicException('GridField doesn\'t have a modelClassName, so it doesn\'t know the columns of this grid.');
 }