在 Amazon SP API 中，发货 ID 是订单配送时创建的唯一标识符。可以通过订单配送 API 获取发货 ID。以下是示例代码：

import amzn_sp_api
from amzn_sp_api.api.order_fulfillment_api import OrderFulfillmentApi
from amzn_sp_api.model.order_id import OrderId

# 使用认证信息进行身份验证
configuration = amzn_sp_api.Configuration()
configuration.access_token = 'YOUR_ACCESS_TOKEN'
api_client = amzn_sp_api.ApiClient(configuration)

# 创建订单 ID 对象
order_id = OrderId()
order_id.amazon_order_id = 'AMAZON_ORDER_ID'

# 使用订单配送 API 获取发货 ID
fulfillment_api = OrderFulfillmentApi(api_client)
get_shipments_response = fulfillment_api.get_shipments(order_id=order_id)
shipment_id = get_shipments_response.payload.shipments[0].shipment_id