title: Using CollectionExpression in QueryDSL
body: <p>In the QueryDSL library, the <code>com.mysema.query.types.expr.SimpleExpression&lt;T&gt;</code> class has a <code>SimpleExpression.in(CollectionExpression&lt;?, ? extends T&gt;)</code> method which is supposed to take an expression which is supposed to return a collection. But I cannot find a way to create an object of type <code>com.mysema.query.types.CollectionExpression&lt;?, ? extends T&gt;</code>. </p>
  
  <p>My query expression looks like this:</p>
  
  <pre><code>QEvent.event.organization.in(expression)
  </code></pre>
  
  <p>where i want the <code>expression</code> to be something like:</p>
  
  <pre><code>QOrganization.organization.country.in("India", "USA")
  </code></pre>
  
  <p>But the second expression is of type <code>com.mysema.query.types.expr.BooleanExpression</code> and I am unable to find a way to convert it to <code>com.mysema.query.types.CollectionExpression&lt;?, ? extends T&gt;</code>.</p>
  
  <p>I looked in the <a href="http://source.mysema.com/static/querydsl/2.1.2/apidocs/" rel="noreferrer">QueryDSL API docs</a> but could not find anything relevant.</p>