How to update BOL entity property value via ABAP code

REPORT PROD_UPDATE_TEST.

PARAMETERS: prd_id TYPE string,
des_val1 TYPE string,
uom_val2 TYPE string,
sta_val3 TYPE string,
icg_val4 TYPE string,
not_val5 TYPE string,
dis_txt6 TYPE string.

DATA:
      lo_core               TYPE REF TO cl_crm_bol_core,
      lo_collection         TYPE REF TO if_bol_entity_col,
      lo_root_entity        TYPE REF TO cl_crm_bol_entity,
      lo_short_text         TYPE REF TO cl_crm_bol_entity,
      lo_uom                TYPE REF TO cl_crm_bol_entity,
      lo_stat               TYPE REF TO cl_crm_bol_entity,
      lo_matb               TYPE REF TO cl_crm_bol_entity,
      lo_note               TYPE REF TO cl_crm_bol_entity,
      lo_dischain           TYPE REF TO cl_crm_bol_entity,
      lo_dischaintxt        TYPE REF TO cl_crm_bol_entity.

DATA:
      lv_view_name          TYPE crmt_view_name,
      lv_query_name         TYPE crmt_ext_obj_name,
      lt_query_parameter    TYPE crmt_name_value_pair_tab,
      ls_query_parameter    LIKE LINE OF lt_query_parameter,
      lo_transaction        TYPE REF TO if_bol_transaction_context,
      lv_success            TYPE abap_bool,
      lv_changed            TYPE abap_bool,
      lv_size               TYPE I.

* get the product
lo_core = cl_crm_bol_core=>get_instance( ).
lo_core->load_component_set( 'PROD_ALL' ).
lo_transaction = lo_core->get_transaction( ).

lv_query_name = 'ProdAdvancedSearchProducts'.

ls_query_parameter-name = 'PRODUCT_ID'.
ls_query_parameter-VALUE = prd_id.
APPEND ls_query_parameter TO lt_query_parameter.

lo_collection = lo_core->query(
iv_query_name               = lv_query_name
it_query_params             = lt_query_parameter
iv_view_name                = lv_view_name ).

lv_size = lo_collection->IF_BOL_BO_COL~SIZE( ).

WRITE:/ 'Product number found:' , lv_size.

ASSERT lv_size = 1.

lo_root_entity = lo_collection->get_first( ).

IF des_val1 IS NOT INITIAL.
* update product description
  lo_short_text = lo_root_entity->get_related_entity( 'ProductShortText' ).

  IF lo_short_text IS INITIAL.
    " HANDLING
    lo_short_text = lo_root_entity->CREATE_RELATED_ENTITY( IV_RELATION_NAME = 'ProductShortText' ).
  ENDIF.

  lo_short_text->set_property( iv_attr_name = 'SHORT_TEXT' iv_value = des_val1 ).
  lo_short_text->set_property( iv_attr_name   = 'LANGU'    iv_value = sy-langu ).
ENDIF.

IF uom_val2 IS NOT INITIAL.
* update base unit
  lo_uom = lo_root_entity->get_related_entity( 'ProductUom' ).

  IF lo_uom IS INITIAL.
    " HANDLING
    lo_uom = lo_root_entity->CREATE_RELATED_ENTITY( IV_RELATION_NAME = 'ProductUom' ).
  ENDIF.

  lo_uom->set_property( iv_attr_name = 'UNIT' iv_value = uom_val2 ).
ENDIF.

IF sta_val3 IS NOT INITIAL.
* update status
  lo_stat = lo_root_entity->get_related_entity( 'ProductStat' ).

  IF lo_stat IS INITIAL.
    lo_stat = lo_root_entity->CREATE_RELATED_ENTITY( IV_RELATION_NAME = 'ProductStat' ).
  ENDIF.

  lo_stat->set_property( iv_attr_name = 'STAT' iv_value = sta_val3 ).
ENDIF.

IF icg_val4 IS NOT INITIAL.
* update item category group
  lo_matb = lo_root_entity->get_related_entity( 'ProductMatBasic' ).

  IF lo_matb IS INITIAL.
    lo_matb = lo_root_entity->CREATE_RELATED_ENTITY( IV_RELATION_NAME = 'ProductMatBasic' ).
  ENDIF.

  lo_matb->set_property( iv_attr_name = 'ITEM_CAT_GROUP' iv_value = icg_val4 ).
ENDIF.

IF not_val5 IS NOT INITIAL.
* update notes
  lo_note = lo_root_entity->get_related_entity( 'ProductLongtext' ).

  IF lo_note IS INITIAL.
    lo_note = lo_root_entity->CREATE_RELATED_ENTITY( IV_RELATION_NAME = 'ProductLongtext' ).
  ENDIF.

  lo_note->set_property( iv_attr_name = 'CONC_LINES' iv_value = not_val5 ).
ENDIF.

IF dis_txt6 IS NOT INITIAL.
* update sales area text
  lo_dischain = lo_root_entity->get_related_entity( 'ProductDistrChain' ).

  IF lo_dischain IS INITIAL.
    lo_dischain = lo_root_entity->CREATE_RELATED_ENTITY( IV_RELATION_NAME = 'ProductDistrChain' ).
  ENDIF.

  lo_dischaintxt = lo_dischain->GET_RELATED_ENTITY( 'ProductDcLongtext' ).

  IF lo_dischaintxt IS INITIAL.
    lo_dischaintxt = lo_dischain->CREATE_RELATED_ENTITY( IV_RELATION_NAME = 'ProductDcLongtext' ).
  ENDIF.

  lo_dischaintxt->set_property( iv_attr_name = 'CONC_LINES' iv_value = dis_txt6 ).
ENDIF.

* execute modification
lo_core->modify( ).
lv_changed = lo_transaction->check_save_needed( ).

CHECK lv_changed EQ abap_true.
lv_success = lo_transaction->save( ).
IF lv_success = abap_true.
  lo_transaction->commit( ).
  WRITE:/ 'Product changed Successfully'.
ELSE.
  lo_transaction->rollback( ).
ENDIF.