1. Enabled Custom Provider (Federated Identity) 2. Fetching user details from identity token 3. Calling a resource server to fetch message for user 

Make sure your read my complete tutorial "Cognito Hosted UI with Amplify in Angular"

Also check out Spring boot resource server

1. Run npm install to install node modules.

2. Update the cognito credentials in aws-exports.js

3. Run ng serve -o to run the project.