public long maybeUpdate(long now) {
            long timeToNextUpdate = clientTelemetrySender.timeToNextUpdate(defaultRequestTimeoutMs);
            if (timeToNextUpdate > 0)
                return timeToNextUpdate;

            // Per KIP-714, let's continue to re-use the same broker for as long as possible.
            if (stickyNode == null) {
                stickyNode = leastLoadedNode(now).node();
                if (stickyNode == null) {
                    log.debug("Give up sending telemetry request since no node is available");
                    return reconnectBackoffMs;
                }
            }

            return maybeUpdate(now, stickyNode);
        }
Add a metadata request to the list of sends if we can make one
clients/src/main/java/org/apache/kafka/clients/NetworkClient.java