Hibernate 自动生成日期值

Question

 <class name="com.traitswu.zone.entity.User" table="user">
        <id name="id" type="int" column="id">
            <generator class="native"/>
        </id>
        <property name="createDate" generated="insert" not-null="true" type="java.util.Date">
            <column name="createDate" sql-type="timestamp" default="CURRENT_TIMESTAMP"/>
        </property>
        <property name="modifiedDate" generated="always" not-null="true" type="java.util.Date">
            <column name="modifiedDate" sql-type="timestamp" default="CURRENT_TIMESTAMP"/>
        </property>
        <property name="userName" type="string" not-null="true" length="50" unique-key="account_unique"/>
        <property name="passWord" type="string" not-null="true" length="50" unique-key="account_unique"/>
    </class>

为什么没有自动生成日期值(exception: Caused by: java.sql.SQLException: Field 'createDate' doesn't have a default value)