Bug 13269 Incorrect operation order in jarpackager
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/jarpackager/JarFileExportOperation.java
return Collections.EMPTY_LIST.iterator();
			
		if (fClassFilesMapContainer == null || !fClassFilesMapContainer.equals(classContainer)) {
			fJavaNameToClassFilesMap= buildJavaToClassMap(classContainer);
			if (fJavaNameToClassFilesMap == null) {
				
				String msg= JarPackagerMessages.getFormattedString("JarFileExportOperation.missingSourceFileAttributeExportedAll", classContainer.getLocation().toFile()); 
				addWarning(msg, null);
				fExportedClassContainers.add(classContainer);
				return getClassesIn(classContainer);
			}
			fClassFilesMapContainer= classContainer;
		}
		ArrayList classFileList= (ArrayList)fJavaNameToClassFilesMap.get(file.getName());
		if (classFileList == null || classFileList.isEmpty()) {
			String msg= JarPackagerMessages.getFormattedString("JarFileExportOperation.classFileOnClasspathNotAccessible", file.getFullPath()); 
			throw new CoreException(new Status(IStatus.ERROR, JavaPlugin.getPluginId(), JavaStatusConstants.INTERNAL_ERROR, msg, null));
		}
		return classFileList.iterator();
	}
	private Iterator getClassesIn(IContainer classContainer) throws CoreException {
		IResource[] resources= classContainer.members();
		List files= new ArrayList(resources.length);
		for (int i= 0; i < resources.length; i++)
			if (resources[i].getType() == IResource.FILE && isClassFile(resources[i]))
				files.add(resources[i]);
		return files.iterator();
	}
	/**
	 * Answers whether the given resource is a Java file.