title: Finding rules with 0 instances in sonar?
body: <p><strong>TL;DR: Basically what I am looking for is a way to get a list of all sonar rules that have 0 issues raised. I could then move all of those to blockers and protect myself from someone adding that issue in the future.</strong> </p>
  
  <p>My company is using sonar and static analysis to help guide refactoring and development of a sizable legacy codebase (~750K LOC). We have had a lot of success by lowering the severity of most rules and then choosing a smaller set of rules to promote up to blocker or critical as we find real issues in the code. This has kept the number of issues we are trying to address at a time manageable so we can actually feel like we are making progress and not drown in the noise of legacy issues.</p>
  
  <p>In particular when we have been bitten by a field or QA issue that sonar could have detected we turn that issue up to a BLOCKER and fix every instance of in. These blockers break the build and we are now assured that we wont add a new instance of the same issue again. This has worked great and has kept a number of what would be nasty bugs from slipping through. </p>
  
  <p>The big problem with that methodology is we need to have an example of every one of those classes of mistake atleast once in the codebase so we could learn that it was important and should be made a blocker. Any issues we haven't already encountered will still be at their default level, I'd like to move all of them up to BLOCKER now so we notice the day they are added. </p>
  
  <p>Edit: Currently we are using 3.7.3 but we are about to upgrade to 5.X.</p>