code: public void goToDir(@NonNull T file) {
          if (!isLoading) {
              mCheckedItems.clear();
              mCheckedVisibleViewHolders.clear();
              refresh(file);
          }
      }
docs: Browses to the designated directory. It is up to the caller verify that the argument is
  in fact a directory. If another directory is in the process of being loaded, this method
  will not start another load.
  <p/>
  Currently selected items are cleared by this operation.
  
  @param file representing the target directory.