* @throws IORuntimeException if an IO error occurs during conversion
     */
    public static String getXContentString(final ToXContent xContent, final MediaType mediaType) {
        try {
            return XContentHelper.toXContent(xContent, mediaType, ToXContent.EMPTY_PARAMS, false).utf8ToString();
        } catch (final IOException e) {
            throw new IORuntimeException(e);
        }
    }

    /**

    public void visit(final QueryBuilderVisitor visitor) {
        queryBuilder.visit(visitor);
    }

    @Override
    public XContentBuilder toXContent(final XContentBuilder builder, final Params params) throws IOException {
        return queryBuilder.toXContent(builder, params);
    }

    @Override
    public void writeTo(final StreamOutput out) throws IOException {
        queryBuilder.writeTo(out);
    }

            final XContentBuilder builder = XContentFactory.jsonBuilder();
            builder.startObject();
            response.toXContent(builder, ToXContent.EMPTY_PARAMS);
            builder.endObject();
            builder.flush();
            try (OutputStream out = builder.getOutputStream()) {