toJson method
Creates a json from the object
Implementation
Map toJson() {
return {
'type': type,
'id': id,
'phone_number': phoneNumber,
'first_name': firstName,
'last_name': lastName,
'vcard': vcard,
'reply_markup': replyMarkup,
'input_message_content': inputMessageContent,
'thumb_url': thumbUrl,
'thumb_width': thumbWidth,
'thumb_height': thumbHeight,
}..removeWhere((_, v) => v == null);
}