Paypal api – Paypal REST Api with retrofit

I am trying to use Paypal REST api with retrofit, but i am getting the following error

{"name":"INVALID_REQUEST","message":"Request is not well-formed, syntactically incorrect, or violates schema.","debug_id":"2689a7ff7bf28","details":[{"field":"/purchase_units","value":"","location":"body","issue":"MISSING_REQUIRED_PARAMETER","description":"A required field / parameter is missing."},{"field":"/intent","value":"","location":"body","issue":"MISSING_REQUIRED_PARAMETER","description":"A required field / parameter is missing."}],"links":[{"href":"https://developer.paypal.com/docs/api/orders/v2/#error-MISSING_REQUIRED_PARAMETER","rel":"information_link","encType":"application/json"}]

here is the request body

Request{method=POST, url=https://api.sandbox.paypal.com/v2/checkout/orders/?%2Fintent=CAPTURE&%2Fpurchase_units=%5B%7B%22currency_code%22%3A%22USD%22%2C%22value%22%3A%22100%22%7D%5D, tags={class retrofit2.Invocation=c.shobaky.tofahaway.orderRequest.Order() [application/json, Bearer A21AAJ-S4HTuRR7ip1zAflRxUBsIVeEkxAAVWM7ZEB7uvn8g-0GBk6Swa3gwWMIiQYBtsXUssvzKWHv6IHDHYIQjREv6ToYow, CAPTURE, [{"currency_code":"USD","value":"100"}]]}}

Here is the code

 Gson gson = new GsonBuilder()
            .setLenient()
            .create();
    Retrofit retrofit = new Retrofit.Builder().baseUrl("https://api.sandbox.paypal.com/v2/checkout/")
            .addConverterFactory(GsonConverterFactory.create(gson)).build();
    orderRequest Order = retrofit.create(orderRequest.class);


    JSONArray Purchase = new JSONArray();
    JSONObject Amount = new JSONObject();
    try {
        Amount.put("currency_code","USD");
        Amount.put("value","100");
    } catch (JSONException e) {
        e.printStackTrace();
    }
    Purchase.put(Amount);


    Call<String> call = Order.Order("application/json","Bearer A21AAJ-S4HTuRR7ip1zAflRxUBsIVeEkxAAVWM7ZEB7uvn8g-0GBk6Swa3gwWMIiQYBtsXUssvzKWHv6IHDHYIQjREv6ToYow","CAPTURE",Purchase);
    call.enqueue(this);

}

@Override
public void onResponse(Call<String> call, Response<String> response) {
    try {
        Log.d("RESPONEPYPAL",call.request().toString()+response.errorBody().string());
    } catch (IOException e) {
        e.printStackTrace();
    }
}

@Override
public void onFailure(Call<String> call, Throwable t) {

}

I got the access token using curl by passing the client id and secret id, so i am almost sure it isn’t about the authorization, it looks like it has something to do with "intent" and "purchase unit"

UPDATE
i used this request before the previous one and also didn’t work

{method=POST, url=https://api.sandbox.paypal.com/v2/checkout/orders/, tags={class retrofit2.Invocation=c.shobaky.tofahaway.orderRequest.Order() [application/json, Bearer A21AAJQvfCFvMKkiWA9anZaEU_hBJ0Pb_TPOQtjqtCjFc39nc_rX6Y5RsCKoYbseMjgiCeGPMhyD5Omqw2tUlgh2EZT-9kiXQ, CAPTURE, [{"amount":{"currency_code":"USD","value":"100"}}]]}}