{"http":400,"request":{"message":{"token":null,"notification":{"title":"Hello","body":"Test notification"}}},"result":{"error":{"code":400,"message":"Recipient of the message is not set.","status":"INVALID_ARGUMENT","details":[{"@type":"type.googleapis.com\/google.rpc.BadRequest","fieldViolations":[{"field":"message","description":"Recipient of the message is not set."}]},{"@type":"type.googleapis.com\/google.firebase.fcm.v1.FcmError","errorCode":"INVALID_ARGUMENT"}]}}}