#vulnerable code 
                                @Test
    public void getMemoryTxs() throws Exception {

        assertNotNull(service);

        Transaction tx = new TestTransaction();
        tx.setTime(0l);

        assertEquals(tx.getHash().getDigestHex(), "08001220d194faf5b314f54c3a299ca9ea086f3f8856c75dc44a1e0c43bcc4d80b47909c");

        Result result = service.newTx(tx);
        assertNotNull(result);
        assertTrue(result.isSuccess());
        assertFalse(result.isFailed());

        List<Transaction> memoryTxs = service.getMemoryTxs();
        assertNotNull(memoryTxs);

        assertEquals(1, memoryTxs.size());

        tx = memoryTxs.get(0);
        assertNotNull(tx);
        assertEquals(tx.getHash().getDigestHex(), "08001220d194faf5b314f54c3a299ca9ea086f3f8856c75dc44a1e0c43bcc4d80b47909c");
    } 
                            #location 9 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    public void getMemoryTxs() throws Exception {

        assertNotNull(service);

        Transaction tx = new TestTransaction();
        tx.setTime(0l);

        assertEquals(tx.getHash().getDigestHex(), "0020c7f397ae78f2c1d12b3edc916e8112bcac576a98444c4c26034c207c9a7ad281");

        Result result = service.newTx(tx);
        assertNotNull(result);
        assertTrue(result.isSuccess());
        assertFalse(result.isFailed());

        List<Transaction> memoryTxs = service.getMemoryTxs();
        assertNotNull(memoryTxs);

        assertEquals(1, memoryTxs.size());

        tx = memoryTxs.get(0);
        assertNotNull(tx);
        assertEquals(tx.getHash().getDigestHex(), "0020c7f397ae78f2c1d12b3edc916e8112bcac576a98444c4c26034c207c9a7ad281");
    }