You can use the following templates:
#foreach($comment in $comments)
<p>$comment.getBody()</p>
#end
#foreach($comment in $comments)
<p>$fieldRenderer.renderWiki2Html($comment.getBody())</p>
#end
<p>Comments:<br />
#if ($comments != $null && $comments.size() > 0)
#foreach($comment in $comments)
#if ($renderer.isCommentInternalServiceDesk($comment))
<span>Internal JIRA SD comment: $comment.getBody()</span><br />
#end
#end
#end
</p>
Fields rendering in templates
$assignee
$fieldRenderer.renderField("T3 Priority Score")
$fieldRenderer.renderFieldById("customfield_10510")
#set( $formatString = "EEE, MMM d, ''yy")
<table>
<thead>
<tr>
<th>Comments</th>
</tr>
</thead>
<tbody>
#foreach($comment in $comments)
<tr>
<td>$dateFormatter.withStyle($formatString).format($comment.getCreated()) $comment.getAuthorFullName()</td>
</tr>
<tr>
<td>
<p>$comment.getBody()</p><hr />
</td>
</tr>
#end
</tbody>
</table>
<p>Public comments for the issue $issue.getKey() with summary "$issue.getSummary()"</p>
<hr />
#if ("$!comments" != "" && $comments.size() > 0)
#foreach($comment in $comments)
#if("$!comment.getRoleLevelId()" == "")
<p>
$comment.getCreated() $comment.getAuthorFullName()
<br />
$comment.getBody()
</p>
#end
#end
#else
<p>The task has not any comments</p>
#end
Show info about all Issue's links, remote links and subtasks
#macro( renderJiraIssues $listTitle, $itemTitle $collection )
<h4>$title</h4>
<ul>
<li>title count: $subTasks.size()</li>
#foreach($issue in $collection)
<li>
<h5>$itemTitle</h5>
<ul>
<li>Key: "$issue.getKey()"</li>
<li>Summary: "$issue.getSummary()"</li>
</ul>
</li>
#end
</ul>
#end
<p>Public comments for the issue $issue.getKey() with summary "$issue.getSummary()"</p><br />
<ul>
<li>
#renderJiraIssues("Subtasks", "Subtask", $subTasks)
</li>
<li>
#renderJiraIssues("Issue Links", "Linked Issue", $links)
</li>
<li>
<h4>Remote Links</h4>
<ul>
<li>Remote Links count: $remoteLinks.size()</li>
#foreach($remoteLink in $remoteLinks)
<li>
<h5>Remote link</h5>
<ul>
<li>Title: "$remoteLink.getTitle()"</li>
<li>Url: $remoteLink.getUrl()</li>
</ul>
</li>
#end
</ul>
</li>
</ul>
Custom fields rendering in templates
#macro( showIssueAttributes $itemIssue )
<li>reporter : $itemIssue.reporter</li>
<li>issue Key : $itemIssue.key</li>
<li>summary : $itemIssue.summary</li>
<li>type: $itemIssue.issueType.name</li>
<li>status: $itemIssue.status.simpleStatus.name</li>
<li>current user: $currentUser</li>
#end
#macro( getCustomFieldsListAttachments $itemIssue )
<ul>
#foreach ($customField in $customFields)
<li>custom field:
<ul>
<li>name: $customField.name</li> ///($customFields is available in v2.0.4 and above)
<li>id: $customField.id</li>
<li>value: $renderer.renderField($issue, $customField.name, "empty")</li>
</ul>
</li>
#end
</ul>
#end
#macro( showAttachments $itemIssue )
<ul>
#foreach ($attachment in $itemIssue.attachments)
<li>attachment:
<ul>
<li>filename: $attachment.filename</li>
<li>id: $attachment.id</li>
<li>url: $baseUrl/secure/attachment/$attachment.id/$attachment.filename</li>
</ul>
</li>
#end
</ul>
#end
<p>Issue:
<ul>
#showIssueAttributes( $issue )
<li>Custom fields:
#getCustomFieldsListAttachments( $issue )
</li>
<li>Attachments:
#showAttachments( $issue )
</li>
<li>Subtasks:
<ul>
#foreach ($subtask in $subTasks)
<li>Subtask
<ul>
#showIssueAttributes( $subtask )
<li>Attachments:
#showAttachments( $subtask )
</li>
</ul>
</li>
#end
</ul>
</li>
</ul>
</p>
$dateFormatter.withStyle("MM.dd.yyyy").format($issue.getCreated())
See also
PDF - Adding Easy PDF Word Issue Templates