spring-data-elasticsearch嵌套对象

spring-data-elasticsearch支持嵌套对象创建，实体类：

@Document(indexName = "xxxx", type = "ttt")
public class Employee {
    @Id
	private String id;
	private String name;
	private Integer age;

    @Field( type = FieldType.Nested)
	private List skills;

指定嵌套对象：

@Field( type = FieldType.Nested)
private List skills;

然后，创建mapping：

elasticsearchTemplate.putMapping(Employee.class);

如果存在嵌套对象，而不做声明，会报异常：

java.lang.IllegalArgumentException: object mapping [skills] can't be changed from nested to non-nested