protected String buildSearch(Map<String, MutableInt> vendor, Map<String, MutableInt> product,
            Set<String> vendorWeighting, Set<String> productWeightings) {

        final StringBuilder sb = new StringBuilder();

        if (!appendWeightedSearch(sb, Fields.PRODUCT, product, productWeightings)) {
            return null;
        }
        sb.append(" AND ");
        if (!appendWeightedSearch(sb, Fields.VENDOR, vendor, vendorWeighting)) {
            return null;
        }
        return sb.toString();
    }
@Test
    public void testBuildSearchBlank() {
        Map<String, MutableInt> vendor = new HashMap<>();
        Map<String, MutableInt> product = new HashMap<>();
        vendor.put("   ", new MutableInt(1));
        product.put("   ", new MutableInt(1));
        Set<String> vendorWeighting = new HashSet<>();
        Set<String> productWeightings = new HashSet<>();

        CPEAnalyzer instance = new CPEAnalyzer();
        String result = instance.buildSearch(vendor, product, vendorWeighting, productWeightings);
        assertNull(result);
    }