code: public void addAlternateKeys(StorableInfo<S> info) {
          if (info == null) {
              throw new IllegalArgumentException();
          }
          for (int i=info.getAlternateKeyCount(); --i>=0; ) {
              addKey(info.getAlternateKey(i));
          }
      }
docs: Adds all of the alternate keys of the given storable as indexes by
  calling {@link #addKey addKey}.
  
  @throws IllegalArgumentException if info is null