#vulnerable code 
                                private void deleteAllLayerGroups() {
        List<String> groups = reader.getLayerGroups().getNames();
        LOGGER.info("Found " + groups.size() + " layerGroups");
        for (String groupName : groups) {
            RESTLayerGroup group = reader.getLayerGroup(groupName);
            if (groups != null) {
                StringBuilder sb = new StringBuilder("Group: ").append(groupName).append(":");
                for (NameLinkElem layer : group.getLayerList()) {
                    sb.append(" ").append(layer);
                }

                boolean removed = publisher.removeLayerGroup(groupName);
                LOGGER.info(sb.toString() + ": removed: " + removed);
                assertTrue("LayerGroup not removed: " + groupName, removed);
            }
        }
    } 
                            #location 8 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                private void deleteAllLayerGroups() {
        List<String> groups = reader.getLayerGroups().getNames();
        LOGGER.info("Found " + groups.size() + " layerGroups");
        for (String groupName : groups) {
            RESTLayerGroup group = reader.getLayerGroup(groupName);
            if (groups != null) {
                StringBuilder sb = new StringBuilder("Group: ").append(groupName).append(":");
                for (NameLinkElem layer : group.getPublishedList()) {
                    sb.append(" ").append(layer);
                }

                boolean removed = publisher.removeLayerGroup(groupName);
                LOGGER.info(sb.toString() + ": removed: " + removed);
                assertTrue("LayerGroup not removed: " + groupName, removed);
            }
        }
    }