Step 2. Generate a unique signature for every user
To allow Raven to fetch the notification details for a user, Raven needs a
unique signature for every user. This can be done by generating a hash of the
userId signed with the Raven API Key.
Since this signature requires Raven API key, it is highly recommended to
create a backend API that generates the hash and sends to the frontend.
Following example shows how to generate a HMAC-SHA256 Signature (hash of
your userId signed with your Raven API Key) in Java -
Add this dependency to pom.xml for using HmacUtils to generate signature