Hi! I'm developing a mobile app with IUGU payment method, for this, I need to build from scratch a plugin. I'm new in programming and OUTSYSTEMS. I don't know how to get the information from API like in the site: https://dev.iugu.com/reference#criar-fatura, that when I post this JS code: 

var data = JSON.stringify({
"ensure_workday_due_date": false,
"items": [
{
"description": "Teste",
"quantity": 1,
"price_cents": 10000
},
{
"description": "Teste1",
"quantity": 1,
"price_cents": 10000
}
],
"payer": {
"address": {
"zip_code": "zip_code",
"street": "street",
"number": "1490",
"district": "district",
"city": "city",
"state": "SP",
"country": "Brasil",
"complement": "Casa"
},
"cpf_cnpj": "cpf_cnpj",
"name": "Bruno"
},
"commissions": {
"cents": 5000
},
"email": "exemple@exemple.com.br",
"due_date": "2020-08-07"
});

var xhr = new XMLHttpRequest();

xhr.addEventListener("readystatechange", function () {
if (this.readyState === this.DONE) {
console.log(this.responseText);
}
});

xhr.open("POST", "https://api.iugu.com/v1/invoices?api_token=");
xhr.setRequestHeader("content-type", "application/json");

returns a Json like this:

{"id":

"ID"

"due_date":

"2020-08-07"

"currency":

"BRL"

"discount_cents":

NULL

"email":

"example@example.com.br"

"items_total_cents":

20000

"notification_url":

NULL

"return_url":

NULL

"status":

"pending"

"tax_cents":

NULL

"total_cents":

20000

}

The code isn't the problem, but I'm not too good at programming and I don't know how to get this JSON data back to my mobile app. Anyone can help me with an article or documentation??

Best Regards