UnsupportedOperationException when ChainingInterceptor is used and addActionError is called.

When the ChainingInterceptor is used to chain between two actions that extends ActionSupport the method getActionErrors returns an unmodifiable collection (from ValidationAwareSupport) and puts it on the second action with setActionErrors. Then it is not possible to use the addActionError method on the second action because an UnsupportedOperationException is thrown.