The documentation portal is undergoing maintenance. During this period, you can't create any new user credentials. If you do, you'll need to recreate the user credential after the maintenance period ends.
Effective in version 10.4.0, you can use Confluent Kafka as sources and targets in streaming mappings using schema registry.
You can use Confluent Kafka to store and retrieve Apache Avro schemas in streaming mappings. Schema registry uses Kafka as its underlying storage mechanism.