<Typography>
  {isSelectedItemLeaf == null && 'No item selected'}
  {isSelectedItemLeaf === true && 'The selected item is a leaf'}
  {isSelectedItemLeaf === false && 'The selected item is a node with children'}
</Typography>
<Box sx={{ minHeight: 352, minWidth: 300 }}>
  <RichTreeView
    items={MUI_X_PRODUCTS}
    apiRef={apiRef}
    onSelectedItemsChange={handleSelectedItemsChange}
  />
</Box>