title: Retrofit Android miss some response from server(not all)
body: <p>when I try to send some request in a for loop, log of the server is ok(all request recieved and all responses sent) but in Android Studio Emulator i have only some those responses not all. here My request code</p>
  
  <pre><code> private void updateDatabase(JsonArray arrayJson) {
      final List&lt;JsonObject&gt; user_cars= new ArrayList&lt;JsonObject&gt;();
      for(JsonElement a : arrayJson){
          String carID = a.getAsString();
          carID=carID.substring(0,carID.length()-1);
          int index = carID.lastIndexOf('/');
          Integer id =Integer.parseInt(carID.substring(index+1));
          Log.e("Index",id.toString());
          AdaClient client = ServiceGenerator.createService(AdaClient.class);
          Call&lt;JsonObject&gt; call = client.retrieveCars(id);
          call.enqueue(new Callback&lt;JsonObject&gt;() {
              @Override
              public void onResponse(Call&lt;JsonObject&gt; call, retrofit2.Response&lt;JsonObject&gt; response) {
                  Log.e("user_cars",response.body().toString());
                  user_cars.add(response.body());
              }
  
              @Override
              public void onFailure(Call&lt;JsonObject&gt; call, Throwable t) {
  
              }
          });
      }
  </code></pre>
  
  <p>The request are 7 as you can see in my log id =</p>
  
  <pre><code>08-29 12:55:20.497 19654-19654/it.uniroma3.adateam.ada E/Index: 1
  08-29 12:55:20.499 19654-19654/it.uniroma3.adateam.ada E/Index: 2
  08-29 12:55:20.505 19654-19654/it.uniroma3.adateam.ada E/Index: 3
  08-29 12:55:20.506 19654-19654/it.uniroma3.adateam.ada E/Index: 4
  08-29 12:55:20.508 19654-19654/it.uniroma3.adateam.ada E/Index: 5
  08-29 12:55:20.511 19654-19654/it.uniroma3.adateam.ada E/Index: 8
  08-29 12:55:20.512 19654-19654/it.uniroma3.adateam.ada E/Index: 9
  </code></pre>
  
  <p>Here logcat</p>
  
  <pre><code>08-29 12:55:20.748 19654-19654/it.uniroma3.adateam.ada E/user_cars: {"id":1,"owner":"raul@raul.raul","car":"http://10.10.10.10:8080/cars/60546/","total_km":null,"tires_km":null,"oil_km":null,"breaks_km":null,"engine_km":null,"insurance_date":null,"vehicle_tax_date":null}
  08-29 12:55:20.826 19654-19654/it.uniroma3.adateam.ada E/user_cars: {"id":3,"owner":"raul@raul.raul","car":"http://10.10.10.10:8080/cars/60550/","total_km":null,"tires_km":null,"oil_km":null,"breaks_km":null,"engine_km":null,"insurance_date":null,"vehicle_tax_date":null}
  08-29 12:55:20.855 19654-19654/it.uniroma3.adateam.ada E/user_cars: {"id":4,"owner":"raul@raul.raul","car":"http://10.10.10.10:8080/cars/60551/","total_km":null,"tires_km":null,"oil_km":null,"breaks_km":null,"engine_km":null,"insurance_date":null,"vehicle_tax_date":null}
  08-29 12:55:20.863 19654-19654/it.uniroma3.adateam.ada E/user_cars: {"id":2,"owner":"raul@raul.raul","car":"http://10.10.10.10:8080/cars/60548/","total_km":null,"tires_km":null,"oil_km":null,"breaks_km":null,"engine_km":null,"insurance_date":null,"vehicle_tax_date":null}
  08-29 12:55:20.915 19654-19654/it.uniroma3.adateam.ada E/user_cars: {"id":8,"owner":"raul@raul.raul","car":"http://10.10.10.10:8080/cars/60550/","total_km":null,"tires_km":null,"oil_km":null,"breaks_km":null,"engine_km":null,"insurance_date":null,"vehicle_tax_date":null}
  08-29 12:55:20.936 19654-19654/it.uniroma3.adateam.ada E/user_cars: {"id":9,"owner":"raul@raul.raul","car":"http://10.10.10.10:8080/cars/60547/","total_km":null,"tires_km":null,"oil_km":null,"breaks_km":null,"engine_km":null,"insurance_date":null,"vehicle_tax_date":null}
  </code></pre>
  
  <p>Here my server response :</p>
  
  <pre><code>[29/Aug/2017 12:55:36] "GET /user-cars/1/ HTTP/1.1" 200                                                                                                                                                    
  [29/Aug/2017 12:55:36] "GET /user-cars/3/ HTTP/1.1" 200                                                                                                                                                   
  [29/Aug/2017 12:55:36] "GET /user-cars/4/ HTTP/1.1" 200                                                                                                                                                    
  [29/Aug/2017 12:55:36] "GET /user-cars/5/ HTTP/1.1" 200                                                                                                                                                    
  [29/Aug/2017 12:55:36] "GET /user-cars/2/ HTTP/1.1" 200                                                                                                                                                    
  [29/Aug/2017 12:55:36] "GET /user-cars/8/ HTTP/1.1" 200                                                                                                                                                    
  [29/Aug/2017 12:55:36] "GET /user-cars/9/ HTTP/1.1" 200
  </code></pre>
  
  <p>As you can see some reponses in logcat is missing the id=5, but is completely random. Why?  </p>