code: @Nullable public View findViewById(int id) {
          if (searchView != null) {
              return searchView.findViewById(id);
          } else if (supportView != null) {
              return supportView.findViewById(id);
          }
          throw new IllegalStateException(ERROR_NO_SEARCHVIEW);
      }
docs: Look for a child view with the given id.  If this view has the given
  id, return this view.
  
  @param id The id to search for.
  @return The view that has the given id in the hierarchy or null