Groovy Script: To generate timestamp 7 days back and pass in request

Hi

I have to generate timestamp in following format.

<end-date>2017-03-23T12:32:19+05:30</end-date>

In this date should be 7 days back. And I have to pass this in request <end-date> parameter.

Can you please suggest Groovy script to do this.

Thanks

Vishal