mobile app uses MC Cordova plug in to receive push notification. Push messages are published from Marketing Cloud and we are trying to use custom keys to add metadata in the payload. The custom keys are enabled and mapped in Marketing Cloud. But in MC doc, https://help.salesforce.com/articleView?id=mc_mp_custom_keys.htm&type=5, it states "mobile app developer must implement custom keys before you can use them". Would someone have reference on what/where mobile app developer need to implement?
Please see the SDK documentation https://salesforce-marketingcloud.github.io/MarketingCloudSDK-iOS/push-notifications/custom-keys.html