Changes to Update Coupon

added the new required request property items/items/product_id

the items/items request property type changed from string to object

added the new optional request property items/items/variant_ids

the request property applies_to_renewals became nullable

the request property disable_if_affiliate_discount became nullable

the request property disable_if_bundle_offer became nullable

the request property disable_if_gateway_discount became nullable

the request property disable_if_quantity_deal became nullable

the request property disable_if_reseller_discount became nullable

the request property disable_if_volume_discount became nullable

the request property expiration_date became nullable

the request property max_uses became nullable

the request property max_uses_per_customer became nullable

the request property min_invoice_price became nullable

the request property payment_method_ids/items became nullable

the request property start_date became nullable

the request property uses_count_mode became nullable

added the new optional request property disable_if_reseller_discount