protected boolean isItemVisible(final File file) {
        if (!showHiddenItems && file.isHidden()) {
            return false;
        }
        return super.isItemVisible(file);
    }
Used by the list to determine whether a file should be displayed or not.
Default behavior is to always display folders. If files can be selected,
then files are also displayed. Set the showHiddenFiles property to show
hidden file. Default behaviour is to hide hidden files. Override this method to enable other
filtering behaviour, like only displaying files with specific extensions (.zip, .txt, etc).

@param file to maybe add. Can be either a directory or file.
@return True if item should be added to the list, false otherwise
android/modules/module_filepicker/src/main/java/com/nononsenseapps/filepicker/FilePickerFragment.java