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
selectedTypesNames = new String[0];
			}
            settings.put(STORE_OVERWRITE_EXISTING_RESOURCES_ID,
                    overwriteExistingResourcesCheckbox.getSelection());
        }
    }
    /**
     *	Answer a boolean indicating whether self's source specification
     *	widgets currently all contain valid values.
     */
    protected boolean validateSourceGroup() {
        
		if (structureProvider == null) {
            setMessage(SOURCE_EMPTY_MESSAGE);
            enableButtonGroup(false);
            return false;
        }
        
        List resourcesToExport = selectionGroup.getAllWhiteCheckedItems();
        if (resourcesToExport.size() == 0){
        	setErrorMessage(DataTransferMessages.FileImport_noneSelected);
        	return false;
        }
        
        enableButtonGroup(true);
        setErrorMessage(null);
        return true;
    }
}