#vulnerable code 
                                @Test
    public void testMultipleReferencesToSameVertex2Instances() {
        Vertex v1 = this.sqlgGraph.addVertex(T.label, "Person", "name", "john");
        this.sqlgGraph.tx().commit();
        //_v1 is in the transaction cache
        //v1 is not
        Vertex _v1 = this.sqlgGraph.v(v1.id());
        Assert.assertEquals("john", v1.value("name"));
        Assert.assertEquals("john", _v1.value("name"));
        v1.property("name", "john1");
        Assert.assertEquals("john1", v1.value("name"));
        Assert.assertEquals("john1", _v1.value("name"));
    } 
                            #location 9 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    public void testMultipleReferencesToSameVertex2Instances() {
        Vertex v1 = this.sqlgGraph.addVertex(T.label, "Person", "name", "john");
        this.sqlgGraph.tx().commit();
        //_v1 is in the transaction cache
        //v1 is not
        Vertex _v1 = this.sqlgGraph.traversal().V(v1.id()).next();
        Assert.assertEquals("john", v1.value("name"));
        Assert.assertEquals("john", _v1.value("name"));
        v1.property("name", "john1");
        Assert.assertEquals("john1", v1.value("name"));
        Assert.assertEquals("john1", _v1.value("name"));
    }