<joined-subclass name="be.me.Teacher" extends="be.me.User">
      <key column="uid" />
   
      <bag name="classes" lazy="false" table="teachers_courses_classes">
         <key column="teacher" />         
         <many-to-many column="class" unique="true"
            class="be.me.SchoolClass" />
         <loader query-ref="classes"/>
      </bag>
   
   </joined-subclass>
   
   <sql-query name="classes">
      <load-collection alias="classes" role="be.me.Teacher.classes" />
      SELECT DISTINCT {classes.*}
      FROM classes
         LEFT JOIN teachers_courses_classes ON teachers_courses_classes.class=classes.id
      WHERE teachers_courses_classes.teacher=:id
   </sql-query>

Caused by: java.lang.NullPointerException
   at org.hibernate.loader.custom.sql.SQLQueryParser.resolveProperties(SQLQueryParser.java:205)
   at org.hibernate.loader.custom.sql.SQLQueryParser.resolveCollectionProperties(SQLQueryParser.java:158)
   at org.hibernate.loader.custom.sql.SQLQueryParser.substituteBrackets(SQLQueryParser.java:121)
   at org.hibernate.loader.custom.sql.SQLQueryParser.process(SQLQueryParser.java:74)
   at org.hibernate.loader.custom.sql.SQLCustomQuery.<init>(SQLCustomQuery.java:133)
   at org.hibernate.engine.query.NativeSQLQueryPlan.<init>(NativeSQLQueryPlan.java:67)
   at org.hibernate.engine.query.QueryPlanCache.getNativeSQLQueryPlan(QueryPlanCache.java:136)
   at org.hibernate.impl.SessionFactoryImpl.checkNamedQueries(SessionFactoryImpl.java:476)
   at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:384)
   at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1327)
   at org.springframework.orm.hibernate3.LocalSessionFactoryBean.newSessionFactory(LocalSessionFactoryBean.java:814)
   at org.springframework.orm.hibernate3.LocalSessionFactoryBean.buildSessionFactory(LocalSessionFactoryBean.java:732)
   at org.springframework.orm.hibernate3.AbstractSessionFactoryBean.afterPropertiesSet(AbstractSessionFactoryBean.java:211)
   at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1368)
   at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1334)
   ... 39 more

<sql-query name="classes">
      <load-collection alias="cl" role="be.me.Teacher.classes" />
      SELECT DISTINCT {cl.*}
      FROM classes cl
         LEFT JOIN teachers_courses_classes course ON course.class=cl.id
      WHERE course.teacher=:id
</sql-query>

SQLLoadable persister = context.getEntityPersisterByAlias( aliasName );
      String suffix = context.getEntitySuffixByAlias( aliasName );

      if ( "*".equals( propertyName ) ) {
         if( !fieldResults.isEmpty() ) {
            throw new QueryException("Using return-propertys together with * syntax is not supported.");
         }         
         aliasesFound++;
         return persister.selectFragment( aliasName, suffix );
      }