What data or structure is contained in the nodes of the element tree?

In Flutter, the element tree represents a structure that links widgets with their rendering and state.

Each node in the element tree contains:

• A reference to the corresponding widget, which describes the UI configuration.
• A reference to child elements, forming a hierarchy.
• State, if the element is a StatefulElement, meaning it is associated with a state.
• BuildContext, which allows access to other elements in the tree.

Thus, the nodes of the element tree store information about the current UI configuration, state, and relationships between widgets, enabling efficient interface updates when changes occur.