priority property
The priority of the message. Valid values are "normal" and "high". On
iOS, these correspond to APNs priorities 5 and 10.
By default, notification messages are sent with high priority, and data messages are sent with normal priority. Normal priority optimizes the client app's battery consumption and should be used unless immediate delivery is required. For messages with normal priority, the app may receive the message with unspecified delay.
When a message is sent with high priority, it is sent immediately, and the app can wake a sleeping device and open a network connection to your server.
For more information, see Setting the priority of a message.
Default value: "high" for notification messages, "normal" for data
messages
Implementation
final String? priority;