class Product{
  String productId;
  ProductBasic productBasic;
  }
 
  class ProductBasic{
   String productId;
   String useType;
   TimeStamp startTimeStamp;
 
   Product product;
  }

<hibernate-mapping>
<class name="com.xy.db.ProductBasic" table="PRODUCTBASIC">
        <composite-id name="id" class="com.xy.db.ProductBasicCompsite">
           
            <one-to-one name="prodcutId" column="PRODUCTID" class="com.xy.db.Product" not-null="true"/>
           
            <key-property name="usetype" type="java.lang.String">
                  <column name="PROCESS_ID" length="16" />
            </key-property>
           
            <key-property name="STARTTTIMESTAMP" type="java.lang.String">
               <column name="STARTTTIMESTAMP" length="16" />
           </key-property>
                       
        </composite-id>

....
    </class>
</hibernate-mapping>

public class ProductBasicCompsite implements Serializable
{
  public BigDecimal prodcutId = null;
  public String usetype = null;
  public String STARTTTIMESTAMP=null;
..setters and getters
override toString, hashcode,equals
}