Offset the service items in the Billing engine.
Offsetting a service item will offset all relevant settlement items of this service item, by creating exact copies of the relevant settlement items with reversed sign.
Depending on customizing, some settlement items will not take part in offsetting the service item and some settlement items will prevent any offsetting at all, which leads to an error.
The processing of all items will be done in one transaction, so in case of any error, nothing will be persisted. Therefore check the errorFlag and error message arrays in the response for any error to detect this case.

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