This step could be used only for Jenkins jobs triggered by
GitHub pull request builder plugin
Step will get code coverage from build. Get collected previously coverage for master. Then
post status to GitHub pull request as comment.
To record master coverage add post build step Record Master Coverage to any job which you think
should be master. Ensure that coverage report is present in a build.
Step get test coverage from Cobertura or Jacoco reports (XML) if they present in build.
They could be created by any tool. Otherwise coverage will be 0.