java.lang.IllegalStateException：同一实体的多个表示形式，@ManyToMany 3个实体

我有3个实体，具有ManyToMany关系：

角色实体：

@Entity
public class Role {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer roleID;
    private String roleName;
    private String description;

    @ManyToMany(cascade = {CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH}, fetch = FetchType.EAGER)
    @JoinTable(name = "role_permission", joinColumns = {@JoinColumn(name = "role_id")}, inverseJoinColumns = {@JoinColumn(name = "permission_id")})
    private Set<Permission> permissions = new LinkedHashSet<Permission>();
}

权限实体：

@Entity
public class Permission {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int permissionID;
    private String permissionName;
    private String description;

    @ManyToMany(cascade = {CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH}, fetch = FetchType.EAGER)
    @JoinTable(name = "permission_functionality", joinColumns = {@JoinColumn(name = "permission_id")}, inverseJoinColumns = {@JoinColumn(name = "functionality_id")})
    private Set<Functionality> functionalities = new LinkedHashSet<>();
}

功能实体：

@Entity
public class Functionality {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    private String name;
}

我做了以下操作：

1. 我创建了3个功能：

   Functionality1, Functionality2, Functionality3
   

2. 然后创建了 2 个权限：

   Permission1 with Functionality1, Functionality2
   
   Permission2 with Functionality2, Functionality3
   

3. 然后创建了一个角色：

   Role1 with Permission1 and Permission2 
   

我遇到以下异常：

java.lang.IllegalStateException：同一实体的多个表示形式 [com.persistence.entity.admin.Functionality#1] 正在合并。分离： [com.persistence.entity.admin.Functionality@4729256a];分离式： [com.persistence.entity.admin.Functionality@56ed25db]