#vulnerable code 
                                public void testPublishDeleteShapeZip() throws FileNotFoundException, IOException {
        if (!enabled()) {
            return;
        }
//        Assume.assumeTrue(enabled);

        String ns = "it.geosolutions";
        String storeName = "resttestshp";
        String layerName = "cities";

        File zipFile = new ClassPathResource("testdata/resttestshp.zip").getFile();

        // known state?
        cleanupTestFT(layerName, ns, storeName);

        // test insert
        boolean published = publisher.publishShp(ns, storeName, layerName, zipFile);
        assertTrue("publish() failed", published);
        assertTrue(existsLayer(layerName));

        RESTLayer layer = reader.getLayer(layerName);

        LOGGER.info("Layer style is " + layer.getDefaultStyle());

        //test delete
        boolean ok = publisher.unpublishFeatureType(ns, storeName, layerName);
        assertTrue("Unpublish() failed", ok);
        assertFalse(existsLayer(layerName));

        // remove also datastore
        boolean dsRemoved = publisher.removeDatastore(ns, storeName);
        assertTrue("removeDatastore() failed", dsRemoved);

    } 
                            #location 23 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public void testPublishDeleteShapeZip() throws FileNotFoundException, IOException {
        if (!enabled()) {
            return;
        }
//        Assume.assumeTrue(enabled);
        deleteAllWorkspaces();
        assertTrue(publisher.createWorkspace(DEFAULT_WS));

//        String ns = "it.geosolutions";
        String storeName = "resttestshp";
        String layerName = "cities";

        File zipFile = new ClassPathResource("testdata/resttestshp.zip").getFile();

        // known state?
        cleanupTestFT(layerName, DEFAULT_WS, storeName);

        // test insert
        boolean published = publisher.publishShp(DEFAULT_WS, storeName, layerName, zipFile);
        assertTrue("publish() failed", published);
        assertTrue(existsLayer(layerName));

        RESTLayer layer = reader.getLayer(layerName);

        LOGGER.info("Layer style is " + layer.getDefaultStyle());

        //test delete
        boolean ok = publisher.unpublishFeatureType(DEFAULT_WS, storeName, layerName);
        assertTrue("Unpublish() failed", ok);
        assertFalse(existsLayer(layerName));

        // remove also datastore
        boolean dsRemoved = publisher.removeDatastore(DEFAULT_WS, storeName);
        assertTrue("removeDatastore() failed", dsRemoved);

    }