The list of discounts applied for the order.
custom_discount: Represents the discount applied on a resent order against the original order.document_level_coupon: Represents the 'Document' level coupons applied to this document. Further, the coupon_id field specifies the coupon ID this discount is based on.document_level_discount: The deduction is due to a discount applied to the invoice sub_total. The discount ID is available as the entity_id.item_level_coupon: Represents the 'Item' level coupons applied to this invoice. Further, the coupon_id field specifies the coupon ID this discount is based on.item_level_discount: The deduction is due to a discount applied to a line item of the invoice. The discount ID is available as the entity_id.promotional_credits: Represents the Promotional Credits item in the invoice. The coupon_id field will be null in this case.prorated_credits: Represents the credit adjustment items in the invoice. The coupon_id field will be null in this case.coupon or a discount, this is the id of the coupon or discount.