When I run this method, I get error "collection was not processed by flush()"


public static boolean isAligned(Session session, CourseRequirement coursereq, InstructionalMethod method){
if (coursereq==null || method == null){
return false;
}
Query query = session.createQuery("SELECT cglo FROM CourseRequirementInstructionalMethod cglo " +
"WHERE cglo.unit.id= :uid AND cglo.method.id= :mid");
query.setLong("uid", coursereq.getId());
query.setLong("mid", method.getId());
List list = query.list();
if (list!=null && list.size()>0){
return true;
}
return false;
}


19:49:21,785 ERROR [AssertionFailure] an assertion failure occured (this may indicate a bug in Hibernate, but is more likely due to unsafe use of the session)
org.hibernate.AssertionFailure: collection [com.cmaps.core.persist.types.AssessmentInstrumentPerformanceObjective.studentperformances] was not processed by flush()
at org.hibernate.engine.CollectionEntry.postFlush(CollectionEntry.java:228)
at org.hibernate.event.def.AbstractFlushingEventListener.postFlush(AbstractFlushingEventListener.java:356)
at org.hibernate.event.def.DefaultAutoFlushEventListener.onAutoFlush(DefaultAutoFlushEventListener.java:65)
at org.hibernate.impl.SessionImpl.autoFlushIfRequired(SessionImpl.java:996)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1141)
at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
at com.cmaps.core.persist.dao.CourseRequirementInstructionalMethodDao.isAligned(CourseRequirementInstructionalMethodDao.java:39)
at com.cmaps.servlet.AjaxUpdateCourseRequirementInstructionalMethodServlet.doAjax(AjaxUpdateCourseRequirementInstructionalMethodServlet.java:38)
at com.cmaps.servlet.AjaxServlet.doGet(AjaxServlet.java:23)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190)
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92)
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126)
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:829)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:601)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Unknown Source)
19:49:21,785 ERROR [[AjaxUpdateCourseRequirementInstructionalMethodServlet]] Servlet.service() for servlet AjaxUpdateCourseRequirementInstructionalMethodServlet threw exception

As the error message says, the error is most likely caused due to unsafe use of the session.
An important rule is for example that never 2 concurrent threads should operate with the same hiberante session.
You have to check, if you use hibernate sessions properly.