Finally specify the following expand clause:

ls_expanded_clause = 'SALESORDERS/LINEITEMS'.
APPEND ls_expanded_clause TO et_expanded_tech_clauses.

Framework Calling

For any other expand statements, the framework is called by calling the method of the superclass, as follows:

METHOD /iwbep/if_mgw_appl_srv_runtime~get_expanded_entity.
IF lv_entityset_name EQ 'BusinessPartnerSet' AND
io_expand->compare_to_tech_names( 'SALESORDERS/LINEITEMS' ) EQ
io_expand->gcs_compare_result-match_equals.
* Code for self expand is called here
ELSE.
*  For any other expand statements call the framework
super->/iwbep/if_mgw_appl_srv_runtime~get_expanded_entity(
EXPORTING
iv_entity_name            = iv_entity_name
iv_entity_set_name        = iv_entity_set_name
iv_source_name            = iv_source_name
io_expand                 = io_expand
it_key_tab                = it_key_tab
it_navigation_path        = it_navigation_path
io_tech_request_context   = io_tech_request_context
IMPORTING
er_entity                 = er_entity
et_expanded_tech_clauses  = et_expanded_tech_clauses
).
ENDIF.
ENDMETHOD.