json中的一个字段名是“user agent”。当我尝试用这个字段名创建流时，ksql不喜欢破折号。我试过单引号，双引号，各种各样的逃避方法——运气不好。
如何从主题中的json中获取该字段，使其位于ksql流中？
以下是我的一些尝试：

ksql> create stream tmpstream (startTimeEpoch bigint, type VARCHAR, src VARCHAR, 'user-agent' varchar) with (KAFKA_TOPIC='foo', VALUE_FORMAT='JSON');
line 1:76: extraneous input ''user-agent'' expecting {'ADD', ...}

ksql> create stream tmpstream (startTimeEpoch bigint, type VARCHAR, src VARCHAR, user-agent varchar) with (KAFKA_TOPIC='foo', VALUE_FORMAT='JSON');
line 1:80: extraneous input '-' expecting {'ADD', ...}

ksql> create stream tmpstream (startTimeEpoch bigint, type VARCHAR, src VARCHAR, "user-agent" varchar) with (KAFKA_TOPIC='foo', VALUE_FORMAT='JSON');

 Message
----------------
 Stream created
----------------
ksql> select * from tmpstream;
Code generation failed for SelectValueMapper
Caused by: Line 1, Column 15: Expression "TMPSTREAM_user" is not an rvalue

ksql> drop stream tmpstream;
 Message
--------------------------------
 Source TMPSTREAM was dropped.
--------------------------------
ksql> create stream tmpstream (startTimeEpoch bigint, type VARCHAR, src VARCHAR, "user\-agent" varchar) with (KAFKA_TOPIC='foo', VALUE_FORMAT='JSON');

 Message
----------------
 Stream created
----------------
ksql> select * from tmpstream;
Code generation failed for SelectValueMapper
Caused by: Line 1, Column 15: Expression "TMPSTREAM_user" is not an rvalue