boolean isTriggerCompleteOrNull() {
		return triggerStatus != STARTED;
	}
Sets an optional request that is suppose to trigger the notification or indication.
This is to ensure that the characteristic value won't change before the callback was set.

@param trigger the operation that triggers the notification, usually a write characteristic
               request that write some OP CODE.
@return The request.
ble/src/main/java/no/nordicsemi/android/ble/AwaitingRequest.java