title: how to select first value in select tag empty(not null) in GSP?
body: <p>Here is my domain class <code>Incident</code></p>
  
  <pre><code> class Incident {
        String status
       Usergroup assignmentGroup
       static hasMany={usergroups:Usergroup}
    }
  </code></pre>
  
  <p>I want to find all incidents by assignmentGroup.I am using GORM criteria for this</p>
  
  <p>this is <code>searchIncident.gsp</code></p>
  
  <pre><code> &lt;tr class="prop"&gt;
         &lt;td valign="top" class="name"&gt;
            &lt;label for="assignmentGroup"&gt;&lt;g:message code="incident.assignmentGroup.label" default="Assignment Group" /&gt;&lt;/label&gt;
         &lt;/td&gt;
         &lt;td valign="top" class="value ${hasErrors(bean: incidentInstance, field: 'assignmentGroup', 'errors')}"&gt;
             &lt;g:select  id="groupSelect" name="assignmentGroup.id" from="${app.Usergroup.list()}" optionKey="id"  value=""  /&gt;
         &lt;/td&gt;
    &lt;/tr&gt;
     &lt;tr class="prop" &gt;
       &lt;td valign="top" class="name"&gt;
          &lt;label for="status"&gt;&lt;g:message code="incident.status.label" default="Status" /&gt;&lt;/label&gt;
       &lt;/td&gt;
       &lt;td valign='top' class='value'&gt;
         &lt;g:select name='status'  from='${[""] + new Incident().constraints.status.inList}'&gt;
         &lt;/g:select&gt;
       &lt;/td&gt; 
      &lt;/tr&gt;
  </code></pre>
  
  <p>In my option tag i must select the first value empty(not null).</p>