如何将自定义列分配给ksql流中的键。在步骤1中，我创建了 messagekey 列并将其指定为 KEY 在第二步中，我将使用udf生成一个uuid并将其分配给 messagekey 它在创建第二个流时给出了这个错误。
错误

Key missing from projection.
The query used to build `ksql_test_step2` must include the key column***messagekey***in its projection.

代码

CREATE STREAM ksql_test_step1 
(messagekey varchar KEY,
explode(payload->scores) as scores,
domain varchar)
 WITH (kafka_topic='test_topic', value_format='JSON');
create stream ksql_test_step2 WITH (value_format='json') as 
select generate_uuid(id,EXTRACTJSONFIELD(scores,'$.source'),
                        EXTRACTJSONFIELD(scores,'$.code'),
                        EXTRACTJSONFIELD(scores,'$.version')) as messagekey,
                        domain
                        from ksql_test_step1  
                        emit changes;