[Enhancement] Add support for Kafka Schema Registry in Logstash Output Plugin

[maggieghamry]

• Version: 7.10
• Support was recently added for the Confluent Schema Registry for Logstash Input Plugins: Add support for Confluent Schema registry and avro serdes #51 but the same was not done for the output. Currently, there is only a third party unsupported plugin.
• Requesting support for a Custom Serializer for Logstash Kafka Output

[fbaligand]

Yes, I vote also for this feature! I really need it!
Thus, currently, if I set value_serializer => "io.confluent.kafka.serializers.KafkaAvroSerializer", the output plugin raises an error, because "avro schema registry" is not set.
So this is really annoying.