toJson method Null safety
Implementation
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data["event"] = this.event;
data["username"] = this.username;
data["displayname"] = this.displayname;
data["callee"] = this.callee;
data["referred_by"] = this.referredBy;
data["replaces"] = this.replaces;
data["srtp"] = this.srtp;
data["headers"] = this.headers;
return data;
}