<class name="ReservedContents" table="SYSTEM_CONTENTS">
      <id name="seq" column="SSC_CONTENTS_SEQ_FK">
         <generator class="native"></generator>
      </id>
      <property name="type" column="SSC_TYPE" type="ContentsEntryType">
         <column name="code" />
      </property>
      <property name="description" column="SSC_DESCRIPTION" />
   </class>

public class ContentsEntryType {
   public static final ContentsEntryType CONTENTS = new ContentsEntryType("CONTENTS");
   public static final ContentsEntryType RECYCLEBIN = new ContentsEntryType("RECYCLEBIN");
   public static final ContentsEntryType WORKBIN = new ContentsEntryType("WORKBIN");
   
   private final String _code;
   
   private ContentsEntryType(String code) {
      this._code = code;
   }
   public String getCode() {
      return _code;
   }
   public String toString() {
      return _code;
   }
}

ReservedContents contents = new ReservedContents();
contents.setType(ContentsEntryType.RECYCLEBIN);
session.save(contetns);