根據以下報錯，知道問題出在哪裏嗎（我在網上找不到)？
org.hibernate.AnnotationException: Associated class not found: java.lang.Integer
有關注解如下：
@ElementCollection(targetClass=Integer.class,fetch= FetchType.LAZY)
@CollectionTable(name="Classification_Groupunit_from",joinColumns=@JoinColumn(name="Id"))
@MapKey(name="Groupunit_from")
@MapKeyClass(String.class)
private Map<String, Integer> Groupunit_from=new HashMap<String, Integer>();//
@ElementCollection(targetClass=Integer.class,fetch= FetchType.LAZY)
@CollectionTable(name="Classification_Groupunit_to",joinColumns=@JoinColumn(name="Id"))
@MapKey(name="Groupunit_to")
@MapKeyClass(String.class)
private Map<String, Integer> Groupunit_to=new HashMap<String, Integer>();
