query specified join fetching, but the owner of the fetched association was not present in the select list 설명과 문제해결

package com.wedul.jpa.school; import lombok.Builder; import lombok.Getter; import lombok.NoArgsConstructor; import javax.persistence.*; import java.util.List; @Getter @NoArgsConstructor @Entity @Table public class Classes { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; private String className; @OneToMany(cascade = CascadeType.ALL, mappedBy = "classes", orphanRemoval =..