Comment by stefan_

It was just updated to extension manifest v3 version and someone went to the trouble of having some sort of field test id mess for it on top of all the nonsense. Doesn't seem like anyone is planning to get rid of it anytime soon.

But the Git history of it is fascinating, starting at the initial merge that got it in that went with the old school trick of "just call X to explain why this is needed" to get your stuff merged. Then every non-trivial change ever to it is inevitably auto-reverted due to some failure before being resubmitted, this must be the "unparalleled Google developer environment" in action - nobody can or bothers to run the tests on a piece of software this big. Half the commits are various formatting nonsense. One third is my favorite - someone making a change to an extension API only to realize the fucking hangout guys sneaked an actual extension into the code base and they will have to update that one to reflect their change. I can feel their anger personally.