private Uuid generateNewClientId() {
        Uuid id = Uuid.randomUuid();
        while (clientInstanceCache.get(id) != null) {
            id = Uuid.randomUuid();
        }
        return id;
    }
Handles client telemetry metrics requests/responses, subscriptions and instance information.
server/src/main/java/org/apache/kafka/server/ClientMetricsManager.java