code: public synchronized boolean isLoaded(LCMSDataSubset subset) {
  
      for (Map.Entry<Object, Set<LCMSDataSubset>> entry : cache.asMap().entrySet()) {
        Object user = entry.getKey();
        if (user == null) {
          // it has already been reclaimed, move on
          // this condition should not be triggered though, because we
          // have eviction listener, which should run cleanup whenever
          // any key in the cache becomes null
          continue;
        }
        Set<LCMSDataSubset> subsets = entry.getValue();
        for (LCMSDataSubset subsetInUse : subsets) {
          if (subsetInUse.contains(subset)) {
            return true;
          }
        }
      }
  
      return false;
    }
docs: Checks among the loaded by all users if this particular subset has already been loaded by
  someone else. <b>Note</b> that if for scan collection you've set a {@link StorageStrategy}
  other than {@link StorageStrategy#STRONG}, this check won't guarantee anything other than the
  scan meta info was loaded. Spectra might have been garbage collected. You can remedy this by
  setting {@link IScanCollection#isAutoloadSpectra(boolean) } true, in which case spectra will be
  automatically loaded, whenever spectrum references are null.