public static String toString(URL url, Charset encoding) throws IOException {
        InputStream inputStream = url.openStream();
        try {
            return toString(inputStream, encoding);
        } finally {
            inputStream.close();
        }
    }
Gets the contents at the given URL.

@param url      The URL source.
@param encoding The encoding name for the URL contents.
@return The contents of the URL as a String.
@throws IOException if an I/O exception occurs.
@since 2.3
pay-java-common/src/main/java/com/egzosn/pay/common/util/IOUtils.java