How to use wildcard in elastalert rules

Question

I need help in ELASTALERT

I have a log message like this :

log.info("Server is started at "+LocalDateTime.now());

and I need to write a query in rule for it: I am writing as

- query:
      query_string:
        query: "message: *Server is*"

It seems like its not working. Can anyone tell me how to do it?