DKB solution provider Crealogix introduced their own authentication solution, which is called Embedded pre-authentication
or Embedded pre-step, which is not a part of Berlin Group PSD2 specification. The solution, as it can be implied from the
name, is a mix of the Embedded and OAuth2 approaches. When requesting for an access token TPP must add a PSU login and password
to a body in the call. TPP must call all PSD2 endpoints with an obtained access token included in the PSD2-AUTHORIZATION
Bearer header.
Sequence Flow
