decodeFileName = function (encodedFileName, charset) {
        /* istanbul ignore if */
        if (!encodedFileName) {
            return;
        }

        if (!characterDecoders[charset]) {
            return;
        }

        // decodes the hexadecimal numbers to charCode in encodedFileName and then decodes with given charset
        return characterDecoders[charset](encodedFileName.replace(regexes.hexCharMatchRegex, decodeHexcode));
    }
Decodes the given filename with given charset
The supported character sets are
iso-8859-1
utf-8

@private
@param {String} encodedFileName - Input encoded file name
@param {String} charset - The character set to be used while decoding
@returns {String} - Returns the decoded filename