POST /sap/opu/odata/sap/API_PURCHASEORDER_PROCESS_SRV/$batch
Content-Type	multipart/mixed; boundary=batch

--batch
Content-Type: multipart/mixed; boundary=changeset_1

  --changeset_1
Content-Type: application/http
Content-Transfer-Encoding: binary

PATCH A_PurOrdPricingElement(PurchaseOrder='4500000665',PurchaseOrderItem='10',PricingDocument='1000000879',PricingDocumentItem='10',PricingProcedureStep='60',PricingProcedureCounter='1') HTTP/1.1
Content-Type: application/json

{
  "ConditionRateValue":"0",
  "ConditionType":"PMP0"
}
--changeset_1
Content-Type: application/http
Content-Transfer-Encoding: binary

PATCH A_PurchaseOrderItem(PurchaseOrder='4500000665',PurchaseOrderItem='10') HTTP/1.1
Content-Type: application/json

{
      "InvoiceIsExpected": false
}

--changeset_1--

--batch--