Your context node classβ inheritance must be changed to: CL_BSP_WD_CONTEXT_NODE_TREE.
You then must redefine the βRefreshβ method and write similar code to the following:
DATA: lr_value_node TYPE REF TO cl_bsp_wd_value_node,
lr_iterator TYPE REF TO if_bol_bo_col_iterator,
lr_root TYPE REF TO if_bsp_wd_tree_node.