Almost everybody who works on web apps knows what JWT (JSON Web Token) is. They become pretty popular and are now widely used.

Without going into details (which can be read e.g. at jwt.io/introduction) JWT is built from three parts divided by dots:

Last week we found out that in some cases our application is showing redundant data on error - for example stacktrace. It happens when there was an error which was handled by the application container which was Jetty. For example, sending a header like X-FORWARDED-PORT: some-not-numeric-value causes NumberFormatException and shows a full stacktrace.

One of my colleagues needs to expose the local running app to an external service. There were simple constraints - the domain name under which service was exposed cannot change (because it needs to be whitelisted) and need to be a subdomain of the company domain.