propagation NOT_SUPPORTED creates failing transaction in JDBC when using ChainedTransactionManager (JDBC + JPA) - jpa

Question

I'm working on an existing Spring application that uses JDBC (DAO's extend NamedParameterJdbcDaoSupport). There were four datasources configured, each with it's own DataSourceTransactionManager. (though only one was registered with tx:annotation-driven for some reason)
I've recently added JPA (Spring-data-JPA) into the application and configured two entityManagerFactories (for now I don't need the other two datasources). I also configured two JpaTransactionManagers and removed the corresponding DataSourceTransactionManagers for these dataSources, since the JpaTransactionManagers can also be used for JDBC transactions. (correct me if I'm wrong)
It appears I need to be able to have distributed transactions, since the two datasources (to two different databases) need to be accessed (through JPA) in one service method. Since I did not have all I need to set up JTA (missing XA-driver for one of the databases) I've decided to give the Spring ChainedTransactionManager a try. Sadly this didn't work out as expected. All works fine if I just call a service method that only uses JPA.
Though when I call an existing service method that uses a JDBC find that has a class level #transactional annotation with it's propagation set to NOT_SUPPORTED and call another service method after that with a JPA call and a #transactional, I get an exception:
Caused by: java.lang.IllegalStateException: Already value [org.springframework.jdbc.datasource.ConnectionHolder#462cf9d9] for key [org.jboss.jca.adapters.jdbc.WrapperDataSource#3fbb4c32] bound to thread [http-/127.0.0.1:8080-5]
at org.springframework.transaction.support.TransactionSynchronizationManager.bindResource(TransactionSynchronizationManager.java:189) [spring-tx-3.2.5.RELEASE.jar:3.2.5.RELEASE]
at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:403) [spring-orm-3.2.5.RELEASE.jar:3.2.5.RELEASE]
After some debugging, I found out that the transactions in Spring get added to a map on a ThreadLocal in the "TransactionSynchronizationManager.bindResource" method. The problem is that when using a JDBC call with #transactional and propogation NOT_SUPPORTED, a transaction is made anyway and registered through that method. When the JpaTransactionManager tries to bind it's resource, it is already on the map (and not marked as void) which causes the error to occur.
Changing the propagation to the default "REQUIRED" for the service call that encapsulates the JDBC call fixes the problem.
I have no idea why Spring is still creating that transaction when the transactional annotation is NOT_SUPPORTED. And if it creates that transaction, it should not bypass the JpaTransactionManager.
So what I'd like to know is if there is some way to tell Spring to use the JpaTransactionManager also when it creates a transaction itself inside the NamedParameterJdbcDaoSupport. (Well actually the JdbcDaoSupport... Well actually the DataSourceUtils)
We're using Spring 3.2.5, spring-data-jpa 1.6.0 and I've used Hibernate 4.2.0 as JpaVendor.
This problem doesn't occur without the ChainedTransactionManager.
Datasources:
<bean id="dataSourceCompta" class="org.springframework.jndi.JndiObjectFactoryBean">
<property name="jndiName" value="java:jboss/datasources/comptaDS"/>
</bean>
<bean id="dataSourceUnisys" class="org.springframework.jndi.JndiObjectFactoryBean">
<property name="jndiName" value="java:jboss/datasources/insoverDS"/>
</bean>
<bean id="dataSourceInsoverwebMysql" class="org.springframework.jndi.JndiObjectFactoryBean">
<property name="jndiName" value="java:jboss/datasources/insoverWebDS"/>
</bean>
<bean id="dataSourceBatch" class="org.springframework.jndi.JndiObjectFactoryBean">
<property name="jndiName" value="java:jboss/datasources/batchDS"/>
</bean>
Single remaining JDBC transaction manager (no JPA counterpart):
<bean id="transactionManagerBatch" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSourceBatch"/>
</bean>
JPA Transaction Managers:
<bean id="jpaUnisysTransactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactoryUnisys"/>
<qualifier value="unisys" />
</bean>
<bean id="jpaMysqlTransactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactoryMysql"/>
<qualifier value="mysql" />
</bean>
My ChainedTransactionManager:
<bean id="chainedTransactionManager" class="org.springframework.data.transaction.ChainedTransactionManager">
<constructor-arg>
<list>
<ref bean="jpaUnisysTransactionManager" />
<ref bean="jpaMysqlTransactionManager" />
</list>
</constructor-arg>
</bean>
JPA Entity manager factories:
<bean name="jpaVendorAdapter" class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>
<bean id="entityManagerFactoryUnisys" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="persistenceXmlLocation" value="classpath:META-INF/some-persistence.xml"/>
<property name="dataSource" ref="dataSourceUnisys"/>
<property name="persistenceUnitName" value="unisysPU"/>
<property name="jpaVendorAdapter" ref="jpaVendorAdapter"/>
<property name="jpaProperties">
<!-- properties -->
</property>
</bean>
<bean id="entityManagerFactoryMysql" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="persistenceXmlLocation" value="classpath:META-INF/some-persistence.xml"/>
<property name="dataSource" ref="dataSourceCompta"/>
<property name="persistenceUnitName" value="mysqlPU"/>
<property name="jpaVendorAdapter" ref="jpaVendorAdapter"/>
<property name="jpaProperties">
<!-- properties -->
</property>
</bean>
For now I've "fixed" this, by changing all the class-level transactional annotations to have propagation.REQUIRED (default) instead of NOT_SUPPORTED. Though I do not really like this solutions, since it might be somebody set those propagations to NOT_SUPPORTED with a good reason. I've also tried SUPPORTED, but using that had the same issue as NOT_SUPPORTED: a transaction was being made anyway by the Spring DataSourceUtils when the query was being executed by the NamedParameterJdbcDaoSupport DAO.
When no transactional annotation is set on the service, all works well too.