code: protected Set common_keySet(boolean includeDiskCache) {
          Set cacheIds = cache.getCacheIds();
  
          /*
           * If the cache is an instanceof CacheProviderWrapper then we know it's not dynacache so
           * we need to check if it supports disk caching. If it doesn't then we don't need incude keys
           * from the disk cache.
           */
          if (cache instanceof CacheProviderWrapper)
              includeDiskCache = ((CacheProviderWrapper) cache).featureSupport.isDiskCacheSupported();
  
          if (includeDiskCache && cache.getIdsSizeDisk() > 0) {
              int index = 0;
              boolean more = true;
              Set cacheIdsDisk = null;
              do {
                  cacheIdsDisk = cache.getIdsByRangeDisk(index, 100);
                  if (cacheIdsDisk != null) {
                      cacheIds.addAll(cacheIdsDisk);
                      if (!cacheIdsDisk.contains(HTODDynacache.DISKCACHE_MORE)) {
                          more = false;
                      }
                  } else {
                      more = false;
                  }
                  index = 1;
              } while (more == true);
              cacheIds.remove(HTODDynacache.DISKCACHE_MORE);
          }
          return cacheIds;
      }
docs: Used by subclasses