If you build a default monolithic application JHipster with Angular and OAuth2 as your type of authentication using Keycloak, everything works apparently well. However, if you want to separate back-end from front-end (for that, you need to set SERVER_API_URL variable defined in the webpack.commons.js, as it is mentioned here), you will get several errors in the console of your web browser, such as,
Access to XMLHttpRequest at 'http://localhost:8080/oauth2/authorization/oidc' (redirected from 'http://localhost:8080/api/account') from origin 'http://localhost:9000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.