sendSticker method
Implementation
Future<Request> sendSticker(String phoneNumber, String mediaId) async {
final Map<String, String> headers = {
'Content-Type': 'application/json',
'Authorization': 'Bearer $accessToken',
};
final Map<String, dynamic> body = {
"messaging_product": "whatsapp",
"recipient_type": "individual",
"to": phoneNumber,
"type": "sticker",
"sticker": {"id": mediaId}
};
await request.post('$fromNumberId/messages', headers, body);
return request;
}