I've seen the same error just once (out of 5 or 6 tries), and, coincidentally, had the same error notified "Failed to store notification: {"type":"RESOURCE_ADDED" etc." with "MethodNotAllowed" at the very same moment, that is, just when the testRemoveXaDatasource test runs.

That's maybe a trail to investigate, maybe it betrays some server-side malfunction. I don't know if it's possible to see server-side logs during agent itests, but it would probably help. I don't know why this error happens.

When I run tests successfully, I also see from times to times this error, but it's distributed randomly in tests, and fortunately or not (rather not), tests pass.