The following code shows how to put list-group-item to panel-collapse.
<!--from www. j av a 2 s. c o m-->
<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
src='http://code.jquery.com/jquery-2.0.2.js'></script>
<link rel="stylesheet" type="text/css"
href="http://netdna.bootstrapcdn.com/bootstrap/3.0.3/css/bootstrap.min.css">
<script type='text/javascript'
src="http://netdna.bootstrapcdn.com/bootstrap/3.0.3/js/bootstrap.min.js"></script>
</head>
<body style='margin:30px'>
<div class="panel-group" id="accordionTwo">
<div class="panel panel-default">
<div class="panel-heading">
<h4 class="panel-title">
<a class="accordion-toggle" data-toggle="collapse"
data-parent="#accordionTwo" href="#collapseFour">Example
Section</a>
</h4>
</div>
<div class="panel-collapse collapse in" id="collapseFour">
<div class="panel-body">Anim pariatur cliche reprehenderit,
enim eiusmod high life accusamus terry richardson ad squid. 3 wolf
moon officia aute, non cupidatat skateboard dolor brunch. Food
truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon tempor,
sunt aliqua put a bird on it squid single-origin coffee nulla
assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer
labore wes anderson cred nesciunt sapiente ea proident. Ad vegan
excepteur butcher vice lomo. Leggings occaecat craft beer
farm-to-table, raw denim aesthetic synth nesciunt you probably
haven't heard of them accusamus labore sustainable VHS.</div>
<div class="list-group">
<a href="#" class="list-group-item">
<span class="badge">1</span>First Item
</a>
<a href="#" class="list-group-item">
<span class="badge">12</span> Second Item</a>
</div>
</div>
</div>
</div>
</body>
</html>