Bug 221649 [Import/Export] ZipFileImportWizard has no option to change the FILE_IMPORT_MASK
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/wizards/datatransfer/WizardArchiveFileResourceImportPage1.java
ArchiveFileManipulations.closeStructureProvider(structureProvider, getShell());
		structureProvider= null;
	}
    /**
     * Returns a content provider for <code>FileSystemElement</code>s that returns
     * only files as children.
     */
    protected ITreeContentProvider getFileProvider() {
        return new WorkbenchContentProvider() {
            public Object[] getChildren(Object o) {
                if (o instanceof MinimizedFileSystemElement) {
                    MinimizedFileSystemElement element = (MinimizedFileSystemElement) o;
                    AdaptableList l = element.getFiles(structureProvider);
                    return l.getChildren(element);
                }
                return new Object[0];
            }
        };
    }
    /**
     *	Answer the root FileSystemElement that represents the contents of the
     *	currently-specified .zip file.  If this FileSystemElement is not
     *	currently defined then create and return it.
     */
    protected MinimizedFileSystemElement getFileSystemTree() {
		disposeStructureProvider();
    	if(ArchiveFileManipulations.isTarFile(sourceNameField.getText())) {
        	TarFile sourceTarFile = getSpecifiedTarSourceFile();
        	if (sourceTarFile == null) {
				return null;