recharge_util library Null safety

Classes

OnRechargePluginDelegate
定义一个抽象类-充值
RechargeUtil
单例的公共类-系统配置,充值,礼物 main.dart中设置 if (Platform.isAndroid) { InAppPurchaseAndroidPlatformAddition.enablePendingPurchases(); } 初始化 initInAppPurchase