code: public Layout previousGeneration() throws FetchException {
          Cursor<StoredLayout> cursor = mLayoutFactory.mLayoutStorage
              .query("storableTypeName = ? & generation < ?")
              .with(getStorableTypeName()).with(getGeneration())
              .orderBy("-generation")
              .fetch();
  
          try {
              if (cursor.hasNext()) {
                  return new Layout(mLayoutFactory, cursor.next());
              }
          } finally {
              cursor.close();
          }
  
          return null;
      }
docs: Returns the previous known generation of the storable's layout, or null
  if none.
  
  @return a layout with a lower generation, or null if none