Whether they are built using the genuine Spring Framework or Spring Boot, such applications are widely developed and deployed these days. By trying to address simple or complex business challenges, products strongly rely on the used framework features in their attempt to offer elegant solutions. Elegant here means correct, clean, and easy to understand and maintain.
In the case of a web application, some requests are handled in a way, while others may need extra pre or post-processing or even a change in the initial request. Generally, Servlet Filters are configured and put in force in order to accommodate such scenarios.