### 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)


} else if (ConcurrentSkipListMap.class == cl) {
            result = new ConcurrentSkipListMap();
        } else {
            try {
                result = cl.newInstance();
            } catch (Exception e) {  }
            if (result == null) {
                try {
                    Constructor<?> constructor = cl.getConstructor(Map.class);
                    result = (Map) constructor.newInstance(Collections.EMPTY_MAP);
                } catch (Exception e) {  }
            }
        }
        if (result == null) {
            result = new HashMap<Object, Object>();
        }
        return result;
    }
    @SuppressWarnings({"unchecked", "rawtypes"})
    private static Object realize0(Object pojo, Class<?> type, Type genericType, final Map<Object, Object> history) {
        if (pojo == null) {
            return null;
        }
        if (type != null && type.isEnum() && pojo.getClass() == String.class) {
            return Enum.valueOf((Class<Enum>) type, (String) pojo);
        }
        if (ReflectUtils.isPrimitives(pojo.getClass())
                && !(type != null && type.isArray()
                && type.getComponentType().isEnum()
                && pojo.getClass() == String[].class)) {