toJson method
Converts to JSON encodable Map
Implementation
Map<String, dynamic> toJson() {
return {
'winner_count': winnerCount,
'unclaimed_prize_count': unclaimedPrizeCount,
'giveaway_message': giveawayMessage?.toJson(),
'is_star_giveaway': isStarGiveaway,
}..removeWhere(_nullFilter);
}