My name is Anton Genkin, I'm a product manager of Bitbucket Server.
As you probably know, adding Commit Graph has been one of the most popular feature requests for Bitbucket Server. We are going to ship it in Bitbucket Server 6.1 release, which is targeted to the end of Feb 2019.
The graph will be displayed in the commits page and will be enabled by default on all instances. There will be no plugin point for apps to offer their own implementation of the graph.
You can find a screenshot of the feature in the attachment. The final version of the UI might have slight changes.
To make sure that you're compliant with these changes, "Commit Graph" feature should be removed from your app running on Bitbucket Server 6.1 and higher, otherwise you will abuse the UI.
If you have any questions please let me know.