CAS 6.x Plain Text Format for OAuth Access Token Removed?

[Justin Isenhour]

I am working on upgrading from CAS 5.3.7 to latest 6.2.1 and after moving new version to our integration environment we found that a number of our OAuth integrated customers are reporting failures.  After investigating I have determined the reason for this is because the format of the access token return from the /accessToken endpoint is now returning a JSON object where as in 5.x versions it returned plain text but default with an option to use JSON format.  After reviewing the commits I see that all support for plain text appears to have been removed in the below commit which has no commentsor explaination and based on the title was a commit to fix a build issue.

https://github.com/apereo/cas/commit/c9b555386f7e165d98d6616b4294f5090ea23758#diff-761a95912cbbe614cb95ccab17095700 

Was support for plain text access tokens removed intentionally?  The documentation for OAuth 6.2.x still shows plain text as being an option.  Is this going to be added back in a future version or am I going to have to get all of my consumers that are currently only supporting plain text to update their apps to use JSON formatted tokens?