LIFERAY: Get the Display Page's Asset inside a Freemarker

get-display-page-asset.ftl

<#assign assetEntryLocalService = serviceLocator.findService("com.liferay.asset.kernel.service.AssetEntryLocalService")/>

<#if Request.INFO_ITEM_DETAILS??>
  <#assign 
    info_item_reference = Request.INFO_ITEM_DETAILS.getInfoItemReference()
    
    className = info_item_reference.getClassName()
    classPK = info_item_reference.getClassPK()
    
    asset = assetEntryLocalService.getEntry(className, classPK)
  />
  ${asset}
</#if>

* Works on Liferay 7.3+.
* Your Freemarker can be a Fragment, Widget Template, Web Content Template, etc; just make sure to use Freemarker's alternative square bracket syntax when inside a Fragment.