public Boolean addToRequestQueue(JRTServerConfigRequest request, boolean forceResponse, CompletionService<Boolean> completionService) {
        // It's no longer delayed if we get here
        request.setDelayedResponse(false);
        try {
            final GetConfigProcessor task = new GetConfigProcessor(this, request, forceResponse);
            if (completionService == null) {
                executorService.submit(task);
            } else {
                completionService.submit(() -> { task.run(); return true; });
            }
            updateWorkQueueMetrics();
            return true;
        } catch (RejectedExecutionException e) {
            request.addErrorResponse(ErrorCode.INTERNAL_ERROR, "getConfig request queue size is larger than configured max limit");
            respond(request);
            return false;
        }
    }
Returns the tenant for this request, empty if there is none
(which on hosted Vespa means that the requesting host is not currently active for any tenant)
configserver/src/main/java/com/yahoo/vespa/config/server/rpc/RpcServer.java