使用spring crudRepository访问数据时出错：找不到类的必需标识符属性

Question

实体类：

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="champion")
public class Champion {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;
    private String name;
    private Integer age;
    @Column(name = "home_town")
    private String homeTown;
    @Column(name = "action_ground")
    private String actionGround;
    @Column(name = "created_at")
    private String createdAt;
    @Column(name = "updated_at")
    private String updatedAt;

    // getters setters
}

存储库类：

@Repository
public interface ChampionRepository extends CrudRepository<Champion, Integer>{

    public Optional<Champion> findById(Integer id);
}

控制台日志：

java.lang.IllegalStateException：找不到类com.marvel.domain.Champion所需的标识符属性！     在org.springframework.data.mapping.PersistentEntity.getRequiredIdProperty（PersistentEntity.java:105）〜[spring-data-commons-2.2.3.RELEASE.jar：2.2.3.RELEASE]     在org.springframework.data.relational.core.mapping.RelationalPersistentEntityImpl.getIdColumn（RelationalPersistentEntityImpl.java:71）〜[spring-data-relational-1.1.3.RELEASE.jar：1.1.3.RELEASE]     在org.springframework.data.jdbc.core.convert.SqlContext.getIdColumn（SqlContext.java:42）〜[spring-data-jdbc-1.1.3.RELEASE.jar：1.1.3.RELEASE]     在org.springframework.data.jdbc.core.convert.SqlGenerator.getIdColumn（SqlGenerator.java:551）〜[spring-data-jdbc-1.1.3.RELEASE.jar：1.1.3.RELEASE]     在org.springframework.data.jdbc.core.convert.SqlGenerator.createFindOneSql（SqlGenerator.java:304）〜