错误：org.apache.ibatis.builder.BuilderException: Ambiguous collection type for property ‘children‘.

写了一个多表查询功能后，项目报错：

Caused by: org.apache.ibatis.builder.BuilderException: Ambiguous collection type for property 'children'. You must specify 'javaType' or 'resultMap'.
	at org.apache.ibatis.builder.xml.XMLMapperBuilder.validateCollection(XMLMapperBuilder.java:415)
	at org.apache.ibatis.builder.xml.XMLMapperBuilder.processNestedResultMappings(XMLMapperBuilder.java:401)
	at org.apache.ibatis.builder.xml.XMLMapperBuilder.buildResultMappingFromContext(XMLMapperBuilder.java:383)
	at org.apache.ibatis.builder.xml.XMLMapperBuilder.resultMapElement(XMLMapperBuilder.java:280)
	at org.apache.ibatis.builder.xml.XMLMapperBuilder.resultMapElement(XMLMapperBuilder.java:253)
	at org.apache.ibatis.builder.xml.XMLMapperBuilder.resultMapElements(XMLMapperBuilder.java:245)
	at org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:118)
	... 77 common frames omitted

注意：Mapper.xml文件中 resultMap的Type类型和方法的返回值是否相同。
Mapper接口：

List<SubjectVo> selectNestedList();

错误写法：

 <resultMap id="selectNestedListMap" type="com.jie.car.service.edu.entity.Subject">

修改为：

 <resultMap id="selectNestedListMap" type="com.jie.car.service.edu.entity.Vo.SubjectVo">