code: public Bundle saveInstanceState(@Nullable Bundle savedInstanceState, String prefix) {
          // handle our extensions
          for (IAdapterExtension<Item> ext : mExtensions.values()) {
              ext.saveInstanceState(savedInstanceState, prefix);
          }
          return savedInstanceState;
      }
docs: add the values to the bundle for saveInstanceState
  
  @param savedInstanceState If the activity is being re-initialized after
  previously being shut down then this Bundle contains the data it most
  recently supplied in Note: Otherwise it is null.
  @param prefix             a prefix added to the savedInstance key so we can store multiple states
  @return the passed bundle with the newly added data