After upgrading to 3.1.2 from 3.0.6 started getting a ClassCastException (see below). I'm sure there is something funky about a class mapping somewhere, but I got quite a handful of mapping files and the exception doesn't give me enough info on where to start looking. Any pointers?

Hibernate version:
3.1.2
Mapping documents:

Code between sessionFactory.openSession() and session.close():

Full stack trace of any exception that occurs:
java.lang.ClassCastException: java.lang.Boolean
at org.hibernate.util.PropertiesHelper.resolvePlaceHolders(PropertiesHelper.java:88)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1173)
at edu.ucsd.som.hibernate.AbstractHibernate3DataStore.initFactory(AbstractHibernate3DataStore.java:437)
at edu.ucsd.som.hibernate.AbstractHibernate3DataStore.getFactory(AbstractHibernate3DataStore.java:401)
at edu.ucsd.som.hibernate.AbstractHibernate3DataStore.createSession(AbstractHibernate3DataStore.java:161)
at edu.ucsd.som.hibernate.AbstractHibernate3DataStore.startSession(AbstractHibernate3DataStore.java:90)
at edu.ucsd.som.onlinepayments.business.PaymentsTestCase.setUp(PaymentsTestCase.java:43)
at com.intellij.rt.execution.junit2.JUnitStarter.main(JUnitStarter.java:32)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:90)

Name and version of the database you are using:
MySQL 4.0

The generated SQL (show_sql=true):

Debug level Hibernate log excerpt:

[main] INFO org.hibernate.cfg.Environment - Hibernate 3.1.2
[main] INFO org.hibernate.cfg.Environment - hibernate.properties not found
[main] INFO org.hibernate.cfg.Environment - using CGLIB reflection optimizer
[main] INFO org.hibernate.cfg.Environment - using JDK 1.4 java.sql.Timestamp handling
[main] DEBUG org.hibernate.cfg.Configuration - Preparing to build session factory with filters : {}
[main] DEBUG org.hibernate.cfg.Configuration - processing extends queue
[main] DEBUG org.hibernate.cfg.Configuration - processing collection mappings
[main] DEBUG org.hibernate.cfg.Configuration - processing native query and ResultSetMapping mappings
[main] DEBUG org.hibernate.cfg.Configuration - processing association property references
[main] DEBUG org.hibernate.cfg.Configuration - processing foreign key constraints

Use your debugger. Put a breakpoint in resolvePlaceHolders and have a look at properties.entrySet(). One of the entry values is a Boolean instead of a String; the corresponding key will give you all the information you need to fix your mapping.