How to set @timestamp timezone?

Hi, magnusbaeck

if I just want to change the @timestamp field, what should I do? the following is my log format:
2016-01-15 09:33:23,650 INFO [127.0.0.1:57799 http-bio-8080-exec-10] com.ins.car.controller.CarOrderController.getInsResult(CarOrderController.java:62) - 2016-01-15 17:33:23,458 getInsResultServlet {....}

as you see, there is two times, 2016-01-15 09:33:23,650 and 2016-01-15 17:33:23,458, the first one is %{+yyyy-MM-dd HH:mm:ss,SSS}, the second one comes from the source message