title: How to group dataset using JSON with Jasper Report?
body: <p>I'm new to Jasper Report, and I'm using JSON as datasource. I have the following dataset, as a sample.</p>
  
  <pre><code>{"Northwind": {
    "Customers": [
     ...
     ],
    "Orders": [
      {
        "ShipPostalCode": 51100,
        "ShippedDate": "1996-07-16",
        "OrderDate": "1996-07-04",
        "OrderID": 10248,
        "Freight": 32.38,
        "RequiredDate": "1996-08-01",
        "ShipCity": "Berlin",
        "ShipCountry": "Germany",
        "EmployeeID": 5,
        "ShipVia": 3,
        "CustomerID": "ALFKI",
        "ShipAddress": "59 rue de l'Abbaye",
        "ShipName": "Vins et alcools Chevalier"
      },
      ...
      {
        "ShipPostalCode": 44087,
        "ShippedDate": "1996-07-10",
        "OrderDate": "1996-07-05",
        "OrderID": 10249,
        "Freight": 11.61,
        "RequiredDate": "1996-08-16",
        "ShipCity": "Munich",
        "ShipCountry": "Germany",
        "EmployeeID": 6,
        "ShipVia": 1,
        "CustomerID": "RATTC",
        "ShipAddress": "Luisenstr. 48",
        "ShipName": "Martinez Gonzalez"
      }
  </code></pre>
  
  <p>I'm passing the <code>ShipCountry</code> as parameter to my subreport, which is working as it should. </p>
  
  <p><a href="https://i.stack.imgur.com/hHFWR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hHFWR.png" alt="enter image description here"></a></p>
  
  <p>However, my template is showing the same data, twice, since it loops my dataset everytime for every object on my subset.
  How group my orders by country ? How can I make to not show it duplicated ? Like this:</p>
  
  <p><a href="https://i.stack.imgur.com/ZTvuJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ZTvuJ.png" alt="enter image description here"></a></p>
  
  <p>My <a href="https://github.com/valterhenrique/reports/blob/stackoverflow_40654817/Demo/demo/samples/jsondatasource/reports/country/country_orders_report.jrxml" rel="nofollow noreferrer">country_orders_report.jrxml</a> and <a href="https://github.com/valterhenrique/reports/blob/stackoverflow_40654817/Demo/demo/samples/jsondatasource/reports/country/country_order_list.jrxml" rel="nofollow noreferrer">country_order_list.jrxml</a> code on GitHub. And <a href="https://github.com/valterhenrique/reports/blob/stackoverflow_40654817/Demo/data/northwind.json" rel="nofollow noreferrer">my whole data</a>, is very small :)</p>
  
  <p>Hope that helps!</p>