How to get Sprint ID from a Webhook when a user starts progress on an Issue?

[Sanel Delic]

I have created a webhook and connected it to a Start progress transition so every time a users starts progress on an issues the webhook is triggered and on the other part I receive the data. 

The only issue I am having is how to transform the Sprint information such as ID or name into strings, as currently it is displayed as:

"customfield_10231":[
   "com.atlassian.greenhopper.service.sprint.Sprint@..."
],

 Any help is highly appreciated.