#vulnerable code 
                                protected FilterWatchListDeletable<Pod, PodList, Boolean, Watch, Watcher<Pod>> withSelector(ClientNonNamespaceOperation<Pod, PodList, DoneablePod, ClientPodResource<Pod, DoneablePod>> pods, LabelSelector selector) {
        FilterWatchListDeletable<Pod, PodList, Boolean, Watch, Watcher<Pod>> answer = pods;
        Map<String, String> matchLabels = selector.getMatchLabels();
        if (matchLabels != null && !matchLabels.isEmpty()) {
            answer = answer.withLabels(matchLabels);
        }
        List<LabelSelectorRequirement> matchExpressions = selector.getMatchExpressions();
        if (matchExpressions != null) {
            for (LabelSelectorRequirement expression : matchExpressions) {
                String key = expression.getKey();
                List<String> values = expression.getValues();
                if (Strings.isNullOrBlank(key)) {
                    log.warn("Ignoring empty key in selector expression %s", expression);
                    continue;
                }
                if (values == null && values.isEmpty()) {
                    log.warn("Ignoring empty values in selector expression %s", expression);
                    continue;
                }
                String[] valuesArray = values.toArray(new String[values.size()]);
                String operator = expression.getOperator();
                switch (operator) {
                    case "In":
                        answer = answer.withLabelIn(key, valuesArray);
                        break;
                    case "NotIn":
                        answer = answer.withLabelNotIn(key, valuesArray);
                        break;
                    default:
                        log.warn("Ignoring unknown operator %s in selector expression %s", operator, expression);
                }
            }
        }
        return answer;
    } 
                            #location 16 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                protected FilterWatchListDeletable<Pod, PodList, Boolean, Watch, Watcher<Pod>> withSelector(ClientNonNamespaceOperation<Pod, PodList, DoneablePod, ClientPodResource<Pod, DoneablePod>> pods, LabelSelector selector) {
        FilterWatchListDeletable<Pod, PodList, Boolean, Watch, Watcher<Pod>> answer = pods;
        Map<String, String> matchLabels = selector.getMatchLabels();
        if (matchLabels != null && !matchLabels.isEmpty()) {
            answer = answer.withLabels(matchLabels);
        }
        List<LabelSelectorRequirement> matchExpressions = selector.getMatchExpressions();
        if (matchExpressions != null) {
            for (LabelSelectorRequirement expression : matchExpressions) {
                String key = expression.getKey();
                List<String> values = expression.getValues();
                if (Strings.isNullOrBlank(key)) {
                    log.warn("Ignoring empty key in selector expression %s", expression);
                    continue;
                }
                if (values == null || values.isEmpty()) {
                    log.warn("Ignoring empty values in selector expression %s", expression);
                    continue;
                }
                String[] valuesArray = values.toArray(new String[values.size()]);
                String operator = expression.getOperator();
                switch (operator) {
                    case "In":
                        answer = answer.withLabelIn(key, valuesArray);
                        break;
                    case "NotIn":
                        answer = answer.withLabelNotIn(key, valuesArray);
                        break;
                    default:
                        log.warn("Ignoring unknown operator %s in selector expression %s", operator, expression);
                }
            }
        }
        return answer;
    }