How to set session timeout to 30 seconds

[oozturkplus]

Hi,
I use Google Dialogflow CX.
If there is no user activity in 30 seconds I want to terminate chatbot session.
There are examples or documentation as below, I tried somethings 
but didn't work. 
https://cloud.google.com/dialogflow/cx/docs/concept/session#long-lasting

If you have a concrete example which is work, please share with me.

Thanks.