AccessController::getPermissionValue

public function getPermissionValue(string $action)
{
	$ruleObject = $this->ruleFactory->createFromAction($action, $this);
	if (! $ruleObject instanceof BaseRule)
	{
		return null;
	}

	$params = ['action' => $action];

	return
		$ruleObject instanceof VariableRule
			? $ruleObject->getPermissionMultiValues($params)
			: $ruleObject->getPermissionValue($params)
	;
}