- According to Spring documentation:
The client sends a request to the application, and the container creates a FilterChain, which contains the Filter instances and Servlet that should process the HttpServletRequest, based on the path of the request URI. In a Spring MVC application, the Servlet is an instance of DispatcherServlet. At most, one Servlet can handle a single HttpServletRequest and HttpServletResponse. - DOC: Spring Security Architecture
In this case, we use the filter chain to deal with a request header in a specific endpoint and divert the flow based in any logic we want to apply.