The supported systems are listed there. It does not list 12, therefore it is not supported. Even if it initially appears to work on 12, then there's every chance it may go wrong later, and you won't be supported. And yes, I've rescued a 6.2 system that had been placed on a version of 12.
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@Rachel Wright (Jira Genie), @Billy Poggi (AUG NOVA, DC), and @Dana Jansen (Confluence Queen) are just some of the folks that lead one of the world's most active Atlassian User Group (AUG)....
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