The ConfigurationClassBeanDefinitionReader hardcodes the behavior that bean definitions from XML always override bean definitions from JavaConfig classes:
I don't see why this decision was made. The normal semantics of using the order in which bean definitions were registered would seem to make sense to apply here as well.
I would expect the following override order to apply:
1. beans defined in foo.xml
2. overridden by beans defined in FooConfig
3. overridden by beans defined in bar.xml
4. overridden by beans defined in BarConfig
Instead it appears the override order is:
1. beans defined in FooConfig
2. overridden by beans defined in BarConfig
3. overridden by beans defined in foo.xml
4. overridden by beans defined in bar.xml
This is not intuitive. Specifically, note the interleaving of beans between both Foo and Bar configurations. The clients who use FooConfig and BarConfig don't care whether the beans defined by those Configuration classes come from XML or java. Yet, the override ordering forces them to be aware of this implementation detail.
I realize changing the behavior outright might present a backwards compatibility issue, so is it possible to add a boolean option to the ApplicationContext to respect the registration ordering regardless of whether the bean definition comes from XML or JavaConfig?