title: JasperReports: Error creating table trying to use CrossTab without column group
body: <p>I'm wondering if there is a way to make a table like this <a href="https://i.stack.imgur.com/6jHVh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/6jHVh.png" alt="enter image description here"></a> using the <code>JapserReports CrossTab</code> or <strong>in any other way</strong> where the row group is the field <code>value7</code>.</p>
  
  <p>The DataSet used is a <code>JRBeanCollectionDataSource(list of SubViews)</code>.</p>
  
  <p>Where SubView is: </p>
  
  <pre><code>public class SubView{
  
    //...
  
    private String value1;
    private String value2;
    private String value3;
    private String value4;
    private String value5;
    private String value6;
    private String value7;
  
    //...getters and setters...
  }
  </code></pre>
  
  <p>Note that there is no need of a column group, but jasper doesn't compile successfully if I don't configure a column group (error message: <code>Crosstab should have at least one column group</code>).</p>