Jira Link are not created for ClearCase UCM project

Problem:
The jira Plugin works correctly for job using git as SCM.
The commit message is scanned and a link to the corresponding Jira issue is created with the method JiraChangeLogAnnotator. (see attachment change-with-link-to-jira-in-git-project.jpg)

But we have also Jobs, that use ClearCase UCM as SCM. The activity is not scanned. So that there is no link to Jira. (see attachment change-without-jira-link-in-CC-project.jpg)