private void downloadFromSource(FileReference fileReference, String client, Spec peerSpec) {
        var fileReferenceDownload = new FileReferenceDownload(fileReference, client, false);
        try {
            var downloading = downloader.downloadFromSource(fileReferenceDownload, peerSpec);
            log.log(FINE, () -> downloading
                    ? "Downloading " + fileReference + " from " + peerSpec.host()
                    : fileReference + " already exists");
        } catch (Exception e) {
            log.log(WARNING, "download from source failed: ", Exceptions.toMessageString(e));
        }
    }
Returns true if empty sentinel config can be returned when a request from a host that is
not part of an application asks for sentinel config
configserver/src/main/java/com/yahoo/vespa/config/server/rpc/RpcServer.java