Using Atlassian Bitbucket v4.9.0.
My enterprise has a large installation of Bitbucket server. We can define webhooks and "Pull Request Notifications" that allow for some automation upon changes to the repository. However, there are a couple things that just don't do anything. The nature of how these features work, combined with our limited access to the support organization for this platform, make it awkward to diagnose why these features aren't working. It also may require debugging issues with Jenkins, another platform that I don't control (even though my support access for Jenkins is better).
For instance, I use the "Http Request Post Receive Hook" with some success, but its scope is limited, as it only works for "push" changes, and not for merges (most of our work is done with pull request merges).
We also use the "Pull Request Notification" feature, that fires when a pull request is created, and spawns a build of the pull request branch.
However, it seems like the "Pull Request Notification" feature only works for some of the "Trigger" events that are available in the interface. Our PRN that fires when a PR is created is looking at OPENED, REOPENED, RESCOPED_FROM, and UPDATED trigger events. I've tried to create additional PRNs in the same project checking for the COMMENTED and MERGED triggers, but it didn't appear that these events ever fired. I would have used these events to provide better automation, but they just don't do anything.
We also have the "Bitbucket Server Webhook to Jenkins" webhook. This isn't as flexible as the HRPRH in terms of what we can fire when the hook fires, but it does appear that it should fire on pull request merges. Unfortunately, this is another feature that just doesn't appear to do anything. It never seems to fire on merges.
I've managed to get builds to spawn on merges, but not with any help from BitBucket. I had to set my Jenkins job to do SCM polling in order for this to work. Unfortunately, using SCM polling is discouraged in our organization (I set it run somewhat rarely to mitigate that somewhat).
