Clarify component scanning of abstract classes with @⁠Lookup methods

Due to changes in gh-19118, classes that contain @⁠Lookup methods are
no longer required to be concrete classes for use with component
scanning; however, the reference documentation still states that such
classes must not be abstract.

This commit therefore removes the outdated reference documentation and
updates the corresponding Javadoc.

See gh-19118
Closes gh-34367

framework-docs/modules/ROOT/pages/core/beans/dependencies/factory-method-injection.adoc

@@ -120,8 +120,6 @@ dynamically generate a subclass that overrides the method.
   subclasses cannot be `final`, and the method to be overridden cannot be `final`, either.
 * Unit-testing a class that has an `abstract` method requires you to subclass the class
   yourself and to supply a stub implementation of the `abstract` method.
-* Concrete methods are also necessary for component scanning, which requires concrete
-  classes to pick up.
 * A further key limitation is that lookup methods do not work with factory methods and
   in particular not with `@Bean` methods in configuration classes, since, in that case,
   the container is not in charge of creating the instance and therefore cannot create
@@ -293,11 +291,6 @@ Kotlin::
 ----
 ======
 
-Note that you should typically declare such annotated lookup methods with a concrete
-stub implementation, in order for them to be compatible with Spring's component
-scanning rules where abstract classes get ignored by default. This limitation does not
-apply to explicitly registered or explicitly imported bean classes.
-
 [TIP]
 ====
 Another way of accessing differently scoped target beans is an `ObjectFactory`/

spring-context/src/main/java/org/springframework/context/annotation/ClassPathScanningCandidateComponentProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -565,9 +565,10 @@ private boolean isConditionMatch(MetadataReader metadataReader) {
 	}
 
 	/**
-	 * Determine whether the given bean definition qualifies as candidate.
-	 * <p>The default implementation checks whether the class is not an interface
-	 * and not dependent on an enclosing class.
+	 * Determine whether the given bean definition qualifies as a candidate component.
+	 * <p>The default implementation checks whether the class is not dependent on an
+	 * enclosing class as well as whether the class is either concrete (and therefore
+	 * not an interface) or has {@link Lookup @Lookup} methods.
 	 * <p>Can be overridden in subclasses.
 	 * @param beanDefinition the bean definition to check
 	 * @return whether the bean definition qualifies as a candidate component