private String URLEnc(String str) {
        try {
            return URLEncoder.encode(str, StandardCharsets.UTF_8.name());
        } catch (UnsupportedEncodingException e) {
            System.err.println("Unable to URLEncode" + str); //$NON-NLS-1$
            return str;
        }
    }
Construct a QueryMap.

@param sizeHint the size hint
gateway/engine/beans/src/main/java/io/apiman/gateway/engine/beans/util/QueryMap.java