JabRef aims for improving user experience. For that, it employs telemetry and, for instance, checks for used features.
The pull requests introducing the first version was https://github.com/JabRef/jabref/pull/2283. Self-hosted alternative Matomo Java Tracker where neglected, because the JabRef team currently does not have the resources to maintain a server.
The ApplicationInsights library that we use supports a special way to submit additional details: https://docs.microsoft.com/en-us/azure/azure-monitor/app/api-custom-events-metrics#properties. Especially, one has to send
source as property.