function getSmartFileExtension(fullPath) {
        DeprecationWarning.deprecationWarning("FileUtils.getSmartFileExtension() has been deprecated. " +
                                              "Please use LanguageManager.getCompoundFileExtension() instead.");
        return LanguageManager.getCompoundFileExtension(fullPath);
    }
Get the file extension (excluding ".") given a path OR a bare filename.
Returns "" for names with no extension.
If the only `.` in the file is the first character,
returns "" as this is not considered an extension.
This method considers known extensions which include `.` in them.
@deprecated Use LanguageManager.getCompoundFileExtension() instead

@param {string} fullPath full path to a file or directory
@return {string} Returns the extension of a filename or empty string if
the argument is a directory or a filename with no extension