Documentation updates around configuration classes

(cherry picked from commit efb5f17)

Author: jhoeller

src/asciidoc/core-beans.adoc

@@ -2907,7 +2907,6 @@ to perform certain actions upon initialization and destruction of your beans.
 
 [TIP]
 ====
-
 The JSR-250 `@PostConstruct` and `@PreDestroy` annotations are generally considered best
 practice for receiving lifecycle callbacks in a modern Spring application. Using these
 annotations means that your beans are not coupled to Spring specific interfaces. For
@@ -6622,13 +6621,16 @@ The behavior could be different according to the scope of your bean. We are talk
 about singletons here.
 ====
 
-[NOTE]
+[TIP]
 ====
 There are a few restrictions due to the fact that CGLIB dynamically adds features at
-startup-time:
+startup-time, in particular that configuration classes must not be final and need to
+have a default constructor with no arguments.
 
-* Configuration classes should not be final
-* They should have a constructor with no arguments
+If you prefer to avoid any CGLIB-imposed limitations, consider declaring your `@Bean`
+methods on non-`@Configuration` classes, e.g. on plain `@Component` classes instead.
+Cross-method calls between `@Bean` methods won't get intercepted then, so you'll have
+to exclusively rely on dependency injection at the field or method level there.
 ====
 
 
@@ -6688,6 +6690,14 @@ This approach simplifies container instantiation, as only one class needs to be
 with, rather than requiring the developer to remember a potentially large number of
 `@Configuration` classes during construction.
 
+[TIP]
+====
+As of Spring Framework 4.2, `@Import` also supports references to regular component
+classes, analogous to the `AnnotationConfigApplicationContext.register` method.
+This is particularly useful if you'd like to avoid component scanning, using a few
+configuration classes as entry points for explicitly defining all your components.
+====
+
 [[beans-java-injecting-imported-beans]]
 ===== Injecting dependencies on imported @Bean definitions