### Environment

* Dubbo version: 2.7.4.1
* Operating System version: macOS Catalina Version 10.15.3
* Java version: 1.8.0_231

### Steps to reproduce this issue

1. 通过telnet调用接口如下
方法(Method)
`public String convert7(UserInfoCondition userInfoCondition) {  }`
参数(Parameter)
`public class UserInfoCondition {
    private List<Map<Integer, UserInfo>> userList;
}`
`public class UserInfo {
    private String accountMobile;
    private String userPassword;
}`

invoke UsesrInfoFacade.convert7({"userList":[{"1":{"accountMobile":"15052234567"}}]})
or
invoke UsesrInfoFacade.convert7({"userList":[{1:{"accountMobile":"15052234567"}}]})

提示如下错误(has a problem)
![image](https://user-images.githubusercontent.com/17045745/77892951-ebd50d00-72a5-11ea-95b0-dd59a68a83cc.png)

到底如何书写这个入参呢?(How to write the parameters)


@Test
    public void testIntToBoolean() throws Exception {
        Map<String, Object> map = new HashMap<>();
        map.put("name", "myname");
        map.put("male", 1);
        map.put("female", 0);
        PersonInfo personInfo = (PersonInfo) PojoUtils.realize(map, PersonInfo.class);
        assertEquals("myname", personInfo.getName());
        assertTrue(personInfo.isMale());
        assertFalse(personInfo.isFemale());
    }
    @Test
    public void testRealizeCollectionWithNullElement() {
        LinkedList<String> listStr = new LinkedList<>();
        listStr.add("arrayValue");
        listStr.add(null);
        HashSet<String> setStr = new HashSet<>();
        setStr.add("setValue");
        setStr.add(null);
        Object listResult = PojoUtils.realize(listStr, LinkedList.class);
        assertEquals(LinkedList.class, listResult.getClass());
        assertEquals(listResult, listStr);
        Object setResult = PojoUtils.realize(setStr, HashSet.class);
        assertEquals(HashSet.class, setResult.getClass());
        assertEquals(setResult, setStr);
    }
    public enum Day {
        SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY
    }
    public static class Parent {