@Test
    public void test_for_issue() throws Exception {
        ParameterizedTypeImpl inner = new ParameterizedTypeImpl(new Type[]{TestB.class}, List.class, List.class);
        ParameterizedTypeImpl outer = new ParameterizedTypeImpl(new Type[]{inner}, TestA.class, TestA.class);
        JSONObject jo = JSONObject.parseObject(json);
        TestA<List<?>> ret = jo.toJavaObject(outer);

        assertTrue(List.class.isInstance(ret.getA()));
        assertEquals(TestB.class.getName(), ret.getA().get(0).getClass().getName());
    }
https://github.com/alibaba/fastjson/issues/3810

@author hnyyghk
@date 2021/06/30 18:40
fastjson1-compatible/src/test/java/com/alibaba/fastjson/issue_3800/Issue3810.java