OptionalkeySchema for the message key. This is only used for Kafka streams. For Kafka, at least one of payload_schema or key_schema must be specified.
OptionalpayloadSchema for the message payload. For Kafka, this is the value schema. Unless the platform supports another schema (e.g. keys for Kafka), this must be specified.
Schema definitions provided directly on the Stream, as opposed to referencing a schema registry. In a future milestone, we will support schema registries through a UC Connection.