private void respond(HttpServerRequest request, HttpStatus status, String body) {
        request.response().setStatusCode(status.getCode()).end(body == null ? "" : body);
    }
The method authorizes HTTP request by user access token or (and) API key.
<p>
    There are four possible use cases:
    <ol>
    <li>Both API key and access token are missed</li>
    <li>Both API key and access token are provided</li>
    <li>Just API key is provided</li>
    <li>Just access token is provided</li>
    </ol>
    The 2nd use case has two sub-cases:
    <ol>
    <li>API key is equal to access token. The credentials could be either access token or API key</li>
    <li>API key is not equal to access token. It could be per-request API key sent by an interceptor</li>
    </ol>
</p>

@param request HTTP request
@return the future of {@link AuthorizationResult}
server/src/main/java/com/epam/aidial/core/server/Proxy.java