docs: public LockSet getFactAtLocation(Location location) throws DataflowAnalysisException {
          if (lockDataflow != null) {
              return lockDataflow.getFactAtLocation(location);
          } else {
              LockSet lockSet = cache.get(location);
              if (lockSet == null) {
                  lockSet = new LockSet();
                  lockSet.setDefaultLockCount(0);
                  if (method.isSynchronized() && !method.isStatic()) {
                      // LockSet contains just the "this" reference
                      ValueNumber instance = vnaDataflow.getAnalysis().getThisValue();
                      lockSet.setLockCount(instance.getNumber(), 1);
                  } else {
                      // LockSet is completely empty - nothing to do
                  }
                  cache.put(location, lockSet);
              }
              return lockSet;
          }
      }