FluidTYPO3\Flux\Form::setExtensionName PHP Method

    public function setExtensionName($extensionName)
    {
        $this->extensionName = $extensionName;
        return $this;
    }

 /**
  * Registers a Form instance to use when TCA for a model object class/table is requested.
  *
  * @param string $className
  * @param Form $form
  * @return void
  */
 public static function registerFormForModelObjectClassName($className, Form $form = NULL)
 {
     if (NULL !== $form && TRUE === isset($GLOBALS['_EXTKEY']) && NULL === $form->getExtensionName()) {
         $form->setExtensionName(GeneralUtility::underscoredToUpperCamelCase($GLOBALS['_EXTKEY']));
     }
     self::$forms['models'][$className] = $form;
 }