code: public void markClustered(boolean clustered) {
          Map<StorableIndex<S>, StorableIndex<S>> replacements = null;
          for (StorableIndex<S> index : this) {
              StorableIndex<S> replacement = index.clustered(clustered);
              if (replacement != index) {
                  if (replacements == null) {
                      replacements = new HashMap<StorableIndex<S>, StorableIndex<S>>();
                  }
                  replacements.put(index, replacement);
              }
          }
          replaceEntries(replacements);
      }
docs: Marks all indexes as clustered or non-clustered.
  
  @param clustered true to mark clustered; false to mark non-clustered
  @see StorableIndex#isClustered()
  @since 1.2