wangduanduan created an issue (kamailio/kamailio#4198)

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### Description

kafka_send in event_route like tcp:timeout, tcp:closed not work

``` event_route[tcp:closed] { if (kafka_send("my_topic", "tcp:closed")) { xlog("L_INFO", "send success tcp:closed"); } } event_route[tcp:timeout] { if (kafka_send("my_topic", "tcp:timeout")) { xlog("L_INFO", "send success tcp:timeout"); } } ```

in log, its show "send success tcp:closed", "send success tcp:timeout", but in kafka web ui, in the **my_topic**, can't find the "tcp:closed" or " tcp:timeout" message.

--- but if the kafka_send in onreply_route, message will be send ok, in the kafka web ui, the "some_route" can be find.

``` onreplay_route[some_route]{ if (kafka_send("my_topic", "some_routet")) { xlog("L_INFO", "send success some_routet"); } } ```

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### Troubleshooting

#### Reproduction

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#### Debugging Data

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#### Log Messages

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#### SIP Traffic

i use tcpdump to capture the traffic between kamailio and kafka. - when use kafka_send in event_route, no packages captured.

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### Possible Solutions

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### Additional Information

* **Kamailio Version** - output of `kamailio -v`

``` 5.6.1 ```

* **Operating System**: centos7

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``` (paste your output here) ```