code: public List<StorageTierView> getTierViewsBelow(String tierAlias) {
      int ordinal = getTierView(tierAlias).getTierViewOrdinal();
      return mTierViews.subList(ordinal + 1, mTierViews.size());
    }
docs: Gets all tierViews before certain tierView. Throws an {@link IllegalArgumentException} if the
  tierAlias is not found.
  
  @param tierAlias the alias of a tierView
  @return the list of {@link StorageTierView}