public static String toString(URL url, String encoding) throws IOException {
        return toString(url, Charsets.toCharset(encoding));
    }
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.
@throws UnsupportedCharsetException thrown instead of {@link UnsupportedEncodingException} in version 2.2 if the encoding is not
                                    supported.
@since 2.1
pay-java-common/src/main/java/com/egzosn/pay/common/util/IOUtils.java