protected boolean isItemVisible(final T file) {
        return (isDir(file) ||
                (mode == MODE_FILE || mode == MODE_FILE_AND_DIR) ||
                (mode == MODE_NEW_FILE && allowExistingFile));
    }
Cab be 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. In case a new file is supposed to be selected,
the {@link #allowExistingFile} determines if existing files are visible

@param file either a directory or file.
@return True if item should be visible in the picker, false otherwise
android/modules/module_filepicker/src/main/java/com/nononsenseapps/filepicker/AbstractFilePickerFragment.java