Assert failing when none of KIP 714 requested metrics are implemented by librdkafka

[emasab]

Description

In case the broker is requesting a set of KIP 714 metrics that isn't matching any of librdkafka implemented metrics an assert is triggered that makes the client process terminate.

How to reproduce

Enable the metric producer.request.latency.avg on the cluster, this particular metric is only present in Java client.
Connect to the cluster with librdkafka 2.5.0.
Happens to clients already connected too.

Checklist

Please provide the following information:

• librdkafka version (2.5.0)
• Apache Kafka version: 3.7.0+
• librdkafka client configuration: enable.metrics.push=true (default)
• Operating system: any
• Provide logs (with debug=.. as necessary) from librdkafka
• Critical issue

Logs

[rdkafka#producer-30][METADATA][7][thrd:main]: ssl://: 1/1 requested topic(s) seen in metadata (lookup by name)
[rdkafka#producer-30][CONTROLLERID][7][thrd:main]: ssl://: ControllerId update 2 -> 0
[rdkafka#producer-30][BROADCAST][7][thrd:main]: Broadcasting state change
[rdkafka#producer-19][PUSH][7][thrd:main]: Serializing metrics
[rdkafka#producer-19][PUSH][7][thrd:main]: Resource attributes count: 0
[rdkafka#producer-19][PUSH][7][thrd:main]: Total metrics to be encoded count: 0
[rdkafka#producer-19][PUSH][7][thrd:main]: Push Telemetry metrics encoded, size: 0
rdbuf.c:834: rd_slice_init_full: Assertion `r == 0' failed.

[pranavrth]

Fixed with v2.5.3.