<class name="Message">
      <composite-id>
         <key-property name="id" type="long">
            <column name="message_id"/>
         </key-property>
         <key-many-to-one name="category"
            column="category_id"
            class="Category"/>
      </composite-id>

      <property name="text" type="string"/>
      <many-to-one name="nextMessage" cascade="save-update" class="Message">
         <column name="next_message_id"/>
         <column name="next_message_category_id"/>
      </many-to-one>
   </class>
   
   <class name="Category">
      <id name="id" type="long" column="category_id">
        <generator class="sequence">
         <param name="sequence">sq_category</param>
        </generator>
      </id>
      
      <property name="name" type="string"/>
      <property name="description" type="string"/>
   </class>

        // childMessage was just saved in a previous transaction,
        // as the "take me to your leader" following "hello world"
        Query query = session.createQuery(
            "select m.nextMessage from Message m where m.nextMessage = :msg").setParameter("msg",
                childMessage);
        Message message = (Message) query.uniqueResult();
        System.out.println(message == null ? "Failed!" : "Success");

org.hibernate.exception.GenericJDBCException: could not execute query
   at org.hibernate.exception.ErrorCodeConverter.handledNonSpecificException(ErrorCodeConverter.java:92)
   at org.hibernate.exception.ErrorCodeConverter.convert(ErrorCodeConverter.java:80)
   at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
   at org.hibernate.loader.Loader.doList(Loader.java:1525)
   at org.hibernate.loader.Loader.list(Loader.java:1505)
   at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:400)
   at org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:271)
   at org.hibernate.impl.SessionImpl.list(SessionImpl.java:791)
   at org.hibernate.impl.QueryImpl.list(QueryImpl.java:74)
   at org.hibernate.impl.AbstractQueryImpl.uniqueResult(AbstractQueryImpl.java:603)
   at sandbox.Main.tryQuery(Main.java:129)
   at sandbox.Main.run(Main.java:118)
   at sandbox.Main.main(Main.java:77)
Caused by: java.sql.SQLException: Unexpected token: , in statement [select message1_.message_id as message1_, message1_.category_id as category2_, message1_.text as text0_, message1_.next_message_id as next4_0_, message1_.next_message_category_id as next5_0_ from Message message0_, Message message1_ where ((message0_.next_message_id, message0_.next_message_category_id)=?  and message0_.next_message_id=message1_.message_id and message0_.next_message_category_id=message1_.category_id)]
   at org.hsqldb.jdbc.jdbcUtil.throwError(Unknown Source)
   at org.hsqldb.jdbc.jdbcPreparedStatement.<init>(Unknown Source)
   at org.hsqldb.jdbc.jdbcConnection.prepareStatement(Unknown Source)
   at org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:379)
   at org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:320)
   at org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:86)
   at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1096)
   at org.hibernate.loader.Loader.doQuery(Loader.java:367)
   at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:208)
   at org.hibernate.loader.Loader.doList(Loader.java:1522)
   ... 9 more
Exception in thread "main"

Hibernate: select message1_.message_id as message1_, message1_.category_id as category2_, message1_.text as text0_, message1_.next_message_id as next4_0_, message1_.next_message_category_id as next5_0_ from Message message0_, Message message1_ where ((message0_.next_message_id, message0_.next_message_category_id)=?  and message0_.next_message_id=message1_.message_id and message0_.next_message_category_id=message1_.category_id)