Developed a scalable enhancement for the vaadin/flow repository, introducing a new HierarchicalTreeData API and InMemoryHierarchicalDataProvider to support richer hierarchical data handling. This work focused on decoupling hierarchical data logic from existing TreeData structures, improving type safety through an additional generic parameter, and refactoring core data-provider classes to enable advanced tree scenarios. The implementation maintained full API compatibility, ensuring existing client code continued to function while enabling more flexible data management. Utilizing Java and object-oriented programming principles, the developer emphasized robust API design and type safety, collaborating closely with other contributors to document and deliver the feature without introducing regressions.