I am getting a large string for response.getJwsResult().

[srjmca]

I am getting a string similar to a bearer token. Using System.currentTimeMillis() as nonce.
How to validate the result on server?

[giacomoferretti]

The result, as the name implies, is a JWS token A.K.A. JSON Web Signature.
You can check the contents of the JWS on websites like https://jwt.io/

Read more here: https://en.wikipedia.org/wiki/JSON_Web_Token