hibernate-Path expected for join问题

Java-primer

代码：
Os类
public class Os {
    private Long id;
    .
    .
    ...
    private Set<OsFeature> osFeatures = new HashSet<OsFeature>();

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name="OsId", unique = true, nullable = false, insertable = true,
     updatable = true)
    public Long getOsId() {
return osId;
     }
     .
     .
     .
   @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "os")
    public Set<OsFeature> getOsFeatures() {
return osFeatures;
    }
}
OsFeature类：
public class OsFeature｛
   
   private Long id;
   
   private Os os;
   .
   .
   .
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "OsFeatureId", unique = true, nullable = false,  insertable = true, updatable = true)
public Long getId() {
    return id;
}
.
.
.
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "OsId", referencedColumnName = "OsId", unique = false, nullable = false, insertable = true, updatable = true)
public Os getOs() {
    return os;
}
}
分析：
    Os与 OsFeature之间的关联为：OneToMany(一对多)；

需求：
    查询Os，需要OsFeature中的某个属性作为查询条件；

HQL语句：
    select model from Os model join model.osFeatures osf where osf.featureString
    like %xxxx%

语句分析：join后面所跟的是 model.osFeatures，osFeatures为Os中的属性，而并不是OsFeature对象
如果join后面跟的是OsFeature对象，将会报Path expected for join异常！