Interface for a basic bus that is implemented by MessageBus so that classes can observe particular event types.
A push message holds the information needed to pass the message on to the appropriate receiver.
Various error types.
A push notification processor that handles registration and new messages from the PushService provided. Starting Push in the Application’s onCreate is recommended.
Implemented by push services like Firebase Cloud Messaging and Amazon Device Messaging SDKs to allow the PushProcessor to manage their lifecycle.