Exploring the virtues of XRootD5: Declarative API

<!--HTML-->Across the years, being the backbone of numerous data management solutions used within the WLCG collaboration, the XRootD framework and protocol became one of the most important building blocks for storage solutions in the High Energy Physics (HEP) community. The latest big milestone for the project, release 5, introduced multitude of architectural improvements and functional enhancements, including the new client side declarative API, which is the main focus of this study. In this contribution we give an overview of the new client API and we discuss its motivation and its positive impact on overall software quality (coupling, cohesion), readability and composability.