public static String toString(URI uri, Charset encoding) throws IOException {
        return toString(uri.toURL(), Charsets.toCharset(encoding));
    }
Gets the contents at the given URI.

@param uri      The URI 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