BadRequest is used when user sends a invalid/malformed JSON request.

GetProblemDetails is used when a error needs to be identified and user needs a specific problem details response corresponding to the identified error.

InvalidCredentials returns a problem details response used when a user enters invalid login credentials.

UnexpectedErrorProblem returns generic problem details response used when an error, about which the user doesn't have to know about, occured.

GoAuthServer is an empty struct used as a representation of a handler for API endpoints.