Function update

packages/react-stately/src/data/useTreeData.ts:452–472

(oldKey: Key, newValue: T)

      });
    },
    update(oldKey: Key, newValue: T) {
      setItems(({items, nodeMap: originalMap}) =>
        updateTree(
          items,
          oldKey,
          oldNode => {
            let node: TreeNode<T> = {
              key: oldNode.key,
              parentKey: oldNode.parentKey,
              value: newValue,
              children: null
            };

            let tree = buildTree(getChildren(newValue), originalMap, node.key);
            node.children = tree.items;
            return node;
          },
          originalMap
        )
      );
    }
  };
}