Bug 14531 Unable to use JarPackager headless
Beginning with the 04/23 Integration build, I am unable to utilize the JarPackager in a headless environment. Specifically, I have defined my own Ant tasks which perform operations including jar packaging. The problem is in JarFileExportOperation.getDirtyEditors(Shell parent). Is it possible to accept null for parent and have the method just return an empty array?
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/jarpackager/JarFileExportOperation.java
* Exports the resources as specified by the JAR package.
	 */
	protected void exportSelectedElements(IProgressMonitor progressMonitor) throws InterruptedException {
		fExportedClassContainers= new HashSet(10);
		int n= fJarPackage.getElements().length;
		for (int i= 0; i < n; i++)
			exportElement(fJarPackage.getElements()[i], progressMonitor);
	}
	/**
	 * Returns an iterator on a list with files that correspond to the
	 * passed file and that are on the classpath of its project.
	 *
	 * @param	file			the file for which to find the corresponding classpath resources
	 * @param	pathInJar		the path that the file has in the JAR (i.e. project and source folder segments removed)
	 * @param	javaProject		the javaProject that contains the file
	 * @return	the iterator over the corresponding classpath files for the given file
	 */
	protected Iterator filesOnClasspath(IFile file, IPath pathInJar, IJavaProject javaProject, IProgressMonitor progressMonitor) throws CoreException {
		
		IFile[] classFiles= fJarPackage.findClassfilesFor(file);
		if (classFiles != null)
			return Arrays.asList(classFiles).iterator();
		if (!isJavaFile(file))
			return Collections.EMPTY_LIST.iterator();
		
		IPath outputPath= javaProject.getOutputLocation();
		IContainer outputContainer;		
		if (javaProject.getProject().getFullPath().equals(outputPath))
			outputContainer= javaProject.getProject();
		else {