java.lang.ClassNotFoundException when plugin contains a transactionized Spring component

The error below is thrown when you try to load a plugin containing a component wrapped into a spring transaction proxy via the web-ui.

The classloader used to load the TransactionProxyFactoryBean doesn't know about the EvaluationManager which will be loaded via the plugin classloader. Therefore the exception will be thrown.

2006-11-14 12:40:58,602 ERROR [com.atlassian.plugin.DefaultPluginManager] addPlugin There was an error loading the descriptor 'Transactionised Evaluation Service' of plugin 'com.atlassian.confluence.extra.evaluation'. Disabling.
com.atlassian.spring.container.ComponentNotFoundException: Failed to find component: Error creating bean with name 'evaluationManager' defined in class path resource [x]: Error setting property values; nested exception is org.springframework.beans.PropertyAccessExceptionsException: PropertyAccessExceptionsException (1 errors); nested propertyAccessExceptions are: [org.springframework.beans.MethodInvocationException: Property 'proxyInterfaces' threw exception; nested exception is java.lang.ClassNotFoundException: com.atlassian.confluence.extra.evaluation.EvaluationManager]
at com.atlassian.spring.container.SpringContainerContext.getComponent(SpringContainerContext.java:106)
at com.atlassian.spring.container.ContainerManager.getComponent(ContainerManager.java:32)
at com.atlassian.confluence.plugin.descriptor.SpringComponentModuleDescriptor.enabled(SpringComponentModuleDescriptor.java:117)
at com.atlassian.plugin.DefaultPluginManager.addPlugin(DefaultPluginManager.java:274)
at com.atlassian.plugin.DefaultPluginManager.scanForNewPlugins(DefaultPluginManager.java:137)
at com.atlassian.plugin.DefaultPluginManager.installPlugin(DefaultPluginManager.java:101)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:284)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:155)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:122)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:56)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:144)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:174)
at $Proxy3.installPlugin(Unknown Source)