int nextCorrelationId() {
        if (SaslClientAuthenticator.isReserved(correlation)) {
            // the numeric overflow is fine as negative values is acceptable
            correlation = SaslClientAuthenticator.MAX_RESERVED_CORRELATION_ID + 1;
        }
        return correlation++;
    }
Add a metadata request to the list of sends if we can make one
clients/src/main/java/org/apache/kafka/clients/NetworkClient.java