#vulnerable code 
                                @Test
    public void testLoadPropertiesOnUpdate() {
        Vertex vertex = this.sqlgGraph.addVertex(T.label, "Person", "property1", "a", "property2", "b");
        this.sqlgGraph.tx().commit();

        vertex = this.sqlgGraph.v(vertex.id());
        vertex.property("property1", "aa");
        assertEquals("b", vertex.value("property2"));

    } 
                            #location 7 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    public void testLoadPropertiesOnUpdate() {
        Vertex vertex = this.sqlgGraph.addVertex(T.label, "Person", "property1", "a", "property2", "b");
        this.sqlgGraph.tx().commit();

        vertex = this.sqlgGraph.traversal().V(vertex.id()).next();
        vertex.property("property1", "aa");
        assertEquals("b", vertex.value("property2"));

    }