This is a plug-in developed by a third party vendor and Atlassian does not provide technical support for it.
Integration of Clover with IBM's UrbanCode AnthillPro. An excerpt from AnthillPro documentation:
The Clover integration uploads Clover coverage results generated by the build to the Coverage tab of the BuildLife.
See: https://developer.ibm.com/urbancode/plugin/clover/