FindBugs: Rank in Html Report

I try to find a way to Insert in findbugs html report the field Rank but I don’t find.
Someone can help me?
Someone can suggest me where findbugs create the report. I mean insert in the report ‘TR’ or insert a class ‘priority-1’ for a particular bug.
I tried to find the code but my little knowledge of project does not permit me to find it.