NWGW - Multi Level $expand not expanded 2nd entity

Hi all,

I am trying to implement a multi level expand (EntityA$expand=EntityB/EntityC) but it is not working for the entity C - it is returning blank).

I can see in debug that the entityset, from the expand method, is being overwritten by a 5 column entity set from standard SAP (only showing entity A and ToItems (Entity B)).

My expand logic is filling the data correctly.

Results:

URL:

../TrolleyHeaderSet?$expand=ToItems/ToMaterials

SEGW:

Association:

Debug:

Expand code:

CASE iv_entity_set_name.
    WHEN 'TrolleyHeaderSet'.
      DATA: "lt_expand  TYPE STANDARD TABLE OF zswm_gw_trolley_expand,
            lt_filters TYPE /iwbep/t_mgw_select_option,
            ls_filter  TYPE /iwbep/s_mgw_select_option,
            lv_filter  TYPE zewm_zone.

      lv_expand_tech_clause = io_tech_request_context->get_expand( ).
      TRANSLATE lv_expand_tech_clause TO UPPER CASE.

  DATA: BEGIN OF ty_expand.
      INCLUDE TYPE zcl_zgw_picking_soluti_mpc_ext=>ts_trolleyheader.
    DATA: toitems TYPE zcl_zgw_picking_soluti_mpc_ext=>tt_trolleyitems,
      tomaterials TYPE zcl_zgw_picking_soluti_mpc_ext=>tt_trolleymaterials,
  END OF ty_expand.

DATA: lt_trolleys  TYPE STANDARD TABLE OF zswm_trolley_ctrl,
 lt_trolley_header TYPE zcl_zgw_picking_soluti_mpc_ext=>tt_trolleyheader,
 lt_trolley_item   TYPE zcl_zgw_picking_soluti_mpc_ext=>tt_trolleyitems,
 lt_trolley_mats   TYPE zcl_zgw_picking_soluti_mpc_ext=>tt_trolleymaterials,
 lt_expand         LIKE STANDARD TABLE OF ty_expand.

DATA: ls_trolley_header TYPE zcl_zgw_picking_soluti_mpc_ext=>ts_trolleyheader,
 ls_trolley_item   TYPE zcl_zgw_picking_soluti_mpc_ext=>ts_trolleyitems,
 ls_materials      TYPE zcl_zgw_picking_soluti_mpc_ext=>ts_trolleymaterials,
 ls_expand         LIKE LINE OF lt_expand.

 SELECT * FROM ztwm_trolleyctrl INTO CORRESPONDING FIELDS OF TABLE lt_trolleys.
      IF sy-subrc <> 0.
        RETURN.
      ENDIF.

      LOOP AT lt_trolleys ASSIGNING FIELD-SYMBOL(<fs_trolleys>).
        MOVE-CORRESPONDING <fs_trolleys> TO ls_trolley_header.
        APPEND ls_trolley_header TO lt_trolley_header.
        MOVE-CORRESPONDING <fs_trolleys> TO ls_trolley_item.
        APPEND ls_trolley_item TO lt_trolley_item.
      ENDLOOP.

      lt_trolley_mats = zcl_wm_picking_solution=>get_materials( ).

      SORT lt_trolley_header BY trolley_type ASCENDING.
      SORT lt_trolley_item   BY trolley_id ASCENDING trolley_type ASCENDING.
      SORT lt_trolley_mats   BY trolley_id ASCENDING trolley_type ASCENDING material ASCENDING.

      DELETE ADJACENT DUPLICATES FROM lt_trolley_header.

      LOOP AT lt_trolley_header ASSIGNING FIELD-SYMBOL(<fs_header>).
        MOVE-CORRESPONDING <fs_header> TO ls_expand.
        LOOP AT lt_trolley_item ASSIGNING FIELD-SYMBOL(<fs_item>) WHERE trolley_type = <fs_header>-trolley_type.
          APPEND <fs_item> TO ls_expand-toitems.
        ENDLOOP.
        LOOP AT lt_trolley_mats ASSIGNING FIELD-SYMBOL(<fs_material>) WHERE trolley_type = <fs_header>-trolley_type.
          APPEND <fs_material> TO ls_expand-tomaterials.
        ENDLOOP.
        APPEND ls_expand TO lt_expand.
        CLEAR ls_expand.
      ENDLOOP.

    WHEN OTHERS.
      RETURN.
  ENDCASE.

  copy_data_to_ref(
    EXPORTING
      is_data = lt_expand
    CHANGING
      cr_data = er_entityset ).

  APPEND lv_expand_tech_clause TO et_expanded_tech_clauses.