#fixed code
                                @Test
    public void testAuthorizeBadDomain() throws Exception {
        TestableConnectionProvider provider = new TestableConnectionProvider();
        // just provide a resource record so the provider returns a directory
        provider.putTestResource(Resource.NEW_NONCE, resourceUrl);

        Session session = provider.createSession();
        Registration registration = Registration.bind(session, locationUrl);

        try {
            registration.preAuthorizeDomain(null);
            fail("null domain was accepted");
        } catch (NullPointerException ex) {
            // expected
        }

        try {
            registration.preAuthorizeDomain("");
            fail("empty domain string was accepted");
        } catch (IllegalArgumentException ex) {
            // expected
        }

        try {
            registration.preAuthorizeDomain("example.com");
            fail("preauthorization was accepted");
        } catch (AcmeException ex) {
            // expected
            assertThat(ex.getMessage(), is("Server does not allow pre-authorization"));
        }

        provider.close();
    }
#vulnerable code 
                                @Test
    public void testAuthorizeBadDomain() throws Exception {
        TestableConnectionProvider provider = new TestableConnectionProvider();
        Session session = provider.createSession();
        Registration registration = Registration.bind(session, locationUrl);

        try {
            registration.authorizeDomain(null);
            fail("null domain was accepted");
        } catch (NullPointerException ex) {
            // expected
        }

        try {
            registration.authorizeDomain("");
            fail("empty domain string was accepted");
        } catch (IllegalArgumentException ex) {
            // expected
        }

        provider.close();
    } 
                            #location 8 
                            #vulnerability type NULL_DEREFERENCE