Bug 296456 [Import/Export] File -> Import filesystem w/cyclical symbolic folder links causes OOME
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/wizards/datatransfer/WizardFileSystemResourceImportPage1.java
/**
     * Check if widgets are enabled or disabled by a change in the dialog.
     * Provided here to give access to inner classes.
     */
    protected void updateWidgetEnablements() {
        super.updateWidgetEnablements();
        enableButtonGroup(ensureSourceIsValid());
    }
    /**
     *	Answer a boolean indicating whether self's source specification
     *	widgets currently all contain valid values.
     */
    protected boolean validateSourceGroup() {
        File sourceDirectory = getSourceDirectory();
        if (sourceDirectory == null) {
            setMessage(SOURCE_EMPTY_MESSAGE);
            enableButtonGroup(false);
            return false;
        }
        if (sourceConflictsWithDestination(new Path(sourceDirectory.getPath()))) {
        	setMessage(null);
            setErrorMessage(getSourceConflictMessage());
            enableButtonGroup(false);
            return false;
        }
        List resourcesToExport = selectionGroup.getAllWhiteCheckedItems();
        if (resourcesToExport.size() == 0){
        	setMessage(null);
        	setErrorMessage(DataTransferMessages.FileImport_noneSelected);
        	return false;