Steps to reproduce:
1. Build the `matterhorn-workflow-workflowoperation` bundle. For instance, run:
mvn clean install -am -pl modules/matterhorn-workflow-workflowoperation
Some temporary files are left in /tmp. If Opencast was build before by another user, the build fails because the other user owns the directory and the files created, and the current mvn process can not modify or delete them.
Builds should not leave "rubbish" behind and building a system should be independent from any other builds.
Workaround (if any):
Delete the directory `/tmp/workflow-workflowoperation/` or make sure it does not exist or that the current user owns it (and its contents) before building Opencast.