How to display selected checkboxes ? Spring-Jsp

I'm new java developer and I need your help. I 've seen already questions-answers with similar topic but still I am not sure how to handle it, so I thought to ask for some help.

I am using Liferay 6.2 & Spring and I have a jsp page with my form that edits a caseType. In this form I want to add a checkbox of Roles (to select the permissions). I'd like to be able to display the selected checkboxes when I edit a caseType. My main issue is that I'm not sure which variables to use.

<form:form name="wblCaseType" method="post" modelAttribute="wblCaseType" action="${saveWblCaseType}">
<form:hidden path="wblCaseTypeId" />
<br/>
    <table style="margin-left:80px">
<tbody>
        <tr>
            <td><form:label path="type"><liferay-ui:message key="type"/></form:label></td>
            <td><form:input path="type" /><form:errors path="type" cssClass="errorClass" /></td>
        </tr>
        <tr>
            <td><form:label path="createRoleIds"><liferay-ui:message key="roles"/></form:label></td>
            <td><form:checkboxes path="createRoleIds" items="${roles}" value="${wblCaseType.createRoleIds}" itemValue="name" itemLabel="roleId" /></td>
    </tr>

Thank you in advance for any help!