eZ\Publish\Core\FieldType\FieldType::onlyEmptyInstance PHP Method

    public function onlyEmptyInstance()
    {
        return false;
    }

 /**
  * Indicates if the field definition of this type can be added to a ContentType with Content instances.
  *
  * @return bool
  */
 public function onlyEmptyInstance()
 {
     return $this->internalFieldType->onlyEmptyInstance();
 }