For a [CartDiscountValueRelative](ctp:api:type:CartDiscountValueRelative), if `applicationMode` is set, the target must be [CartDiscountPatternTarget](ctp:api:type:CartDiscountPatternTarget).
If `applicationMode` is `ProportionateDistribution` or `EvenDistribution`, the [CartDiscountPatternTarget](ctp:api:type:CartDiscountPatternTarget) `triggerPattern` must be non-empty.
If either conditions are not met, an [InvalidOperation](ctp:api:type:InvalidOperationError) error is returned.
New value to set.