 The CollapsingPostFilter collapses a result set on a field.
 <p>
 The ExpandComponent expands the collapsed groups for a single page.
 <p>
 http parameters:
 <p>
 expand=true <br>
 expand.rows=5 <br>
 expand.sort=field asc|desc<br>
 expand.q=*:* (optional, overrides the main query)<br>
 expand.fq=type:child (optional, overrides the main filter queries)<br>
 expand.field=field (mandatory if the not used with the CollapsingQParserPlugin)<br></div>
</li>
</ul>
</div>
<div class="summary">
<ul class="blockList