code: public synchronized boolean isAlive() {
          if(original!=null && original.isAlive())
              return true;
  
          for (Entry<String,RangeSet> e : usages.entrySet()) {
              Job j = Jenkins.getInstance().getItemByFullName(e.getKey(),Job.class);
              if(j==null)
                  continue;
  
              Run firstBuild = j.getFirstBuild();
              if(firstBuild==null)
                  continue;
  
              int oldest = firstBuild.getNumber();
              if(!e.getValue().isSmallerThan(oldest))
                  return true;
          }
          return false;
      }
docs: Returns true if any of the builds recorded in this fingerprint
  is still retained.
  
  <p>
  This is used to find out old fingerprint records that can be removed
  without losing too much information.