Using the new ABAP 7.40 constructor operation CONV for converting data-types on the fly. In this example we need to pass the name to the get_as_string method. i_delivery is type vbeln_vl yet a string is expected. CONV # takes car of the conversion in-line.

abap_type_conversion.abap

  method payment_terms_text.
    data(text) = new lcl_text_reader( )->get_as_string(
                                           id     = '0002'
                                           name   = conv #( i_delivery )
                                           object = 'VBBK'
                                         ).

    data proxy_text_collection type zxi_text_collection_text_tab.
    data proxy_text_line like line of proxy_text_collection.

    proxy_text_line-content_text-language_code = cl_abap_syst=>get_language( ).
    proxy_text_line-content_text-content = text.
    append proxy_text_line to proxy_text_collection.
    r_result = proxy_text_collection.
  endmethod.