Hi! Just faced with the issue with Bitbucket cloud webhooks. At webhook status page I see error 500 and in Jenkins logs I see:
WARNING o.e.j.s.h.ContextHandler$Context#log: Error while serving https://jenkins.my.domain/bitbucket-hook/
net.sf.json.JSONException: JSONObject["username"] not found.
After quick investigation I recognized that Bitbucket depricate and remove username field from the api request. More details here: