The Telemetry end-to-end example is a package of the Eclipse IoT Packages™ project. It describes itself as:
A package showing telemetry data acquisition end-to-end: Microcontroller firmware to cloud side data processing, using Drogue IoT and Apache Kafka in the process.
As the content is part of the IoT packages project, we only link the tutorial. You can take a look at: https://www.eclipse.org/packages/packages/telemetry-e2e/