you can use Regular expression as Pivovarov mentioned. I did not tried it but it should work.

if you can parse string with JSON parse then can know string is JSON..

otherwise it can be simple normal Text.

Good day.

Thank you Francesco,

Appreciate your quick help on API. It will work for me.

Hello Francesco, 

How are you?

I have question how can we call API request.

I tried to create device and GET request to pas login & password but not working..

Did you make something to call REST api to GET/POST action.

Regards,

Abhishek