private String toUPlusString(char c) {
        String hexString = Integer.toHexString(c);
        switch (hexString.length()) {
            case 1:
                return "U+000" + hexString;
            case 2:
                return "U+00" + hexString;
            case 3:
                return "U+0" + hexString;
            case 4:
                return "U+" + hexString;
            default:
                throw new RuntimeException("Unreachable.");
        }
    }
Collect a set of attribues and values from the data part of a PI.

<p>
The bulk of this method and associated methods that follow it here are
copied from the nu.validator.htmlparser.impl.Tokenizer class, with
appropriate modifications.
</p>

@see nu.validator.htmlparser.impl.Tokenizer
@see nu.validator.htmlparser.impl.ErrorReportingTokenizer
src/nu/validator/checker/XmlPiChecker.java