ControllerBased::loadProgressSteps

private function loadProgressSteps(string $permissionEntityType): array
{
	if (!isset($this->progressStepsCache[$permissionEntityType]))
	{
		$this->progressStepsCache[$permissionEntityType] = $this->controller->hasProgressSteps()
			? $this->controller->getProgressSteps($permissionEntityType)
			: []
		;
		if (!empty($this->progressStepsCache[$permissionEntityType]))
		{
			sort($this->progressStepsCache[$permissionEntityType], SORT_STRING);
		}
	}

	return $this->progressStepsCache[$permissionEntityType];
}