private static Optional<Version> getVespaVersionFromRequest(HttpRequest request) {
        return Optional.ofNullable(request.getProperty("vespaVersion"))
                .filter(s -> !s.isEmpty())
                .map(Version::fromString);
    }
Operations on applications (delete, wait for config convergence, restart, application content etc.)

@author hmusum
configserver/src/main/java/com/yahoo/vespa/config/server/http/v2/ApplicationHandler.java