IllegalAccessError when creating CGLIB proxies for package-private classes using Spring DevTools

I hit this error using gradle bootRun when spring-boot-devtools is on the classpath:

o.s.aop.framework.CglibAopProxy : Unable to proxy method [...] because it is package-visible across different ClassLoaders: All calls to this method via a proxy will NOT be routed to the target instance.
<snip>
java.lang.IllegalAccessError: class Foo$$EnhancerBySpringCGLIB$$8345c360 cannot access its superclass Foo

If I remove spring-boot-devtools, the application starts fine. I’m guessing this is due to the classloader architecture of spring-boot-devtools…

[wilkinsona]

@kartoffelsup In your case the problem is because your application is split into multiple modules which can cause problems with DevTools’ restart class loader.

The proxy for BarServiceImpl is loaded by the restart class loader but BarServiceImpl itself is loaded by the app class loader. A package is scoped to the class loader that defined it so, in this case, we end up with two different org.bar.devtools.autoconfig.demo packages and a package-private type in one of those package is not visible to a type in the other of those packages.

You can fix the problem by adding bar to the restart class loader using META-INF/spring-devtools.properties:

restart.include.bar=/bar-.+\.jar

[kartoffelsup]

Ahh, thank you @wilkinsona 😃! Sorry for the inconvenience.