promotion | object or string | Yes | - | Official Google Merchant API Promotion body as an object or JSON string, sent as-is. Use Google’s REST camelCase field names exactly. Required fields per Google: promotionId, contentLanguage, targetCountry, redemptionChannel, and attributes with longTitle, offerType, couponValueType, productApplicability, genericRedemptionCode (for GENERIC_CODE offers), and promotionEffectiveTimePeriod startTime/endTime. Inserting with an existing promotionId replaces the promotion. Example: {“promotionId”: “summer_sale_20”, “contentLanguage”: “en”, “targetCountry”: “US”, “redemptionChannel”: [“ONLINE”], “attributes”: {“longTitle”: “20% off all shirts”, “offerType”: “GENERIC_CODE”, “genericRedemptionCode”: “SUMMER20”, “couponValueType”: “PERCENT_OFF”, “percentOff”: “20”, “productApplicability”: “ALL_PRODUCTS”, “promotionEffectiveTimePeriod”: {“startTime”: “2026-08-01T00:00:00Z”, “endTime”: “2026-08-31T23:59:59Z”}}} |