(Optional) The file that stores the build identifier
The <buildIdFile> element specifies the file that stores the build identifier. The build identifier is stored as an integer number in the file. The packager tool increments the value each time the BAR package is built.
If you use this element, don't include any <buildId> elements in the application descriptor file.
A PCDATA value representing the name of the build file in your application root folder. The default value created by the IDE is buildnum.