Syntax to get Uploaded File Name from Message File Upload Bean

First import DataObject from this package
import oracle.cabo.ui.data.DataObject;

Then make a reference to the MessageFileUpload bean
like below, where MessageFileUpload is the Id of my MessageFileUpload Item

DataObject fileUploadData = pageContext.getNamedDataObject("MessageFileUpload");

so to get file name of uploaded file with extension.

using the following syntax in processFormRequest

String strFileName=null;      
if(fileUploadData != null)
        {
         strFileName= fileUploadData.selectValue(null,"UPLOAD_FILE_NAME").toString();
        }