I have recently noticed that Atlassian updated documentation related to AP.cookie methods. There are two new methods - ‘saveLocalStorage’ and ‘readLocalStorage’.
But it seems that these methods are still not added to AP.cookie in both Confluence Cloud and Jira Cloud.
Thanks for bringing this to our attention. These methods are actually internal implementation methods of the AP.cookie module and were not supposed to appear in the publicly facing documentation.
We are currently working to remove these methods from the documentation. In the meantime, the save and read methods of AP.cookie were already rewired to use these new methods internally, so you will have the same result as using the publicly available API.