#vulnerable code 
                                @Test
    @ConditionalIgnoreRule.ConditionalIgnore(condition = StandardTierOnlyRule.class)
    public void testQueryTwin() throws IOException, InterruptedException, IotHubException, NoSuchAlgorithmException, URISyntaxException, ModuleClientException
    {
        addMultipleDevices(MAX_DEVICES);

        // Add same desired on multiple devices
        final String queryProperty = PROPERTY_KEY_QUERY + UUID.randomUUID().toString();
        final String queryPropertyValue = PROPERTY_VALUE_QUERY + UUID.randomUUID().toString();

        setDesiredProperties(queryProperty, queryPropertyValue, MAX_DEVICES);

        // Query multiple devices having same property
        final String where = "is_defined(properties.desired." + queryProperty + ")";
        SqlQuery sqlQuery = SqlQuery.createSqlQuery("*", SqlQuery.FromType.DEVICES, where, null);
        Thread.sleep(MAXIMUM_TIME_FOR_IOTHUB_PROPAGATION_BETWEEN_DEVICE_SERVICE_CLIENTS);
        Query twinQuery = sCDeviceTwin.queryTwin(sqlQuery.getQuery(), PAGE_SIZE);

        for (int i = 0; i < MAX_DEVICES; i++)
        {
            if (sCDeviceTwin.hasNextDeviceTwin(twinQuery))
            {
                DeviceTwinDevice d = sCDeviceTwin.getNextDeviceTwin(twinQuery);
                assertNotNull(d.getVersion());

                assertEquals(TwinConnectionState.DISCONNECTED.toString(), d.getConnectionState());

                for (Pair dp : d.getDesiredProperties())
                {
                    assertEquals(buildExceptionMessage("Unexpected desired property key, expected " + queryProperty + " but was " + dp.getKey(), internalClient), queryProperty, dp.getKey());
                    assertEquals(buildExceptionMessage("Unexpected desired property value, expected " + queryPropertyValue + " but was " + dp.getValue(), internalClient), queryPropertyValue, dp.getValue());
                }
            }
        }
        assertFalse(sCDeviceTwin.hasNextDeviceTwin(twinQuery));
        removeMultipleDevices(MAX_DEVICES);
    } 
                            #location 35 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    @ConditionalIgnoreRule.ConditionalIgnore(condition = StandardTierOnlyRule.class)
    public void testQueryTwin() throws IOException, InterruptedException, IotHubException, GeneralSecurityException, URISyntaxException, ModuleClientException
    {
        addMultipleDevices(MAX_DEVICES);

        // Add same desired on multiple devices
        final String queryProperty = PROPERTY_KEY_QUERY + UUID.randomUUID().toString();
        final String queryPropertyValue = PROPERTY_VALUE_QUERY + UUID.randomUUID().toString();

        setDesiredProperties(queryProperty, queryPropertyValue, MAX_DEVICES);

        // Query multiple devices having same property
        final String where = "is_defined(properties.desired." + queryProperty + ")";
        SqlQuery sqlQuery = SqlQuery.createSqlQuery("*", SqlQuery.FromType.DEVICES, where, null);
        Thread.sleep(MAXIMUM_TIME_FOR_IOTHUB_PROPAGATION_BETWEEN_DEVICE_SERVICE_CLIENTS);
        Query twinQuery = sCDeviceTwin.queryTwin(sqlQuery.getQuery(), PAGE_SIZE);

        for (int i = 0; i < MAX_DEVICES; i++)
        {
            if (sCDeviceTwin.hasNextDeviceTwin(twinQuery))
            {
                DeviceTwinDevice d = sCDeviceTwin.getNextDeviceTwin(twinQuery);
                assertNotNull(d.getVersion());

                assertEquals(TwinConnectionState.DISCONNECTED.toString(), d.getConnectionState());

                for (Pair dp : d.getDesiredProperties())
                {
                    assertEquals(buildExceptionMessage("Unexpected desired property key, expected " + queryProperty + " but was " + dp.getKey(), internalClient), queryProperty, dp.getKey());
                    assertEquals(buildExceptionMessage("Unexpected desired property value, expected " + queryPropertyValue + " but was " + dp.getValue(), internalClient), queryPropertyValue, dp.getValue());
                }
            }
        }
        assertFalse(sCDeviceTwin.hasNextDeviceTwin(twinQuery));
        removeMultipleDevices(MAX_DEVICES);
    }