OAF - Making mandatory Attachement Mandatory

Case - Need to make the Attachment Bean mandatory. Use the below line of code in PFR.

OAMessageAttachmentLinkBean oamessageattachmentlinkbean = (OAMessageAttachmentLinkBean)oawebbean.findChildRecursive("");

String attachVal = (String)oamessageattachmentlinkbean.getAttributeValue(oapagecontext.getRenderingContext(),TEXT_ATTR);

if("None".equals(attachVal))
{
throw new OAException(“Attachment mandatory”,OAException.ERROR);
}