In the Javadoc, it is not clear that a deployment resource must end on .bpmn or .bpmn20.xml to be parsed as a process definition. This sometimes leads to confusion (e.g. https://forum.camunda.org/t/no-process-definition-after-deployment/2580).
- the Javadoc of DeploymentBuilder (or where it fits best) lists the resource suffixes that are interpreted during deployment and what happens with those resources
Also consider logging a warning if model instances are added to the deployment where the resource name won't trigger deployment.