Document @⁠Conditional gating of nested @⁠Configuration classes

Closes gh-36831

Signed-off-by: Dennis-Mircea Ciupitu <dennis.mircea.ciupitu@gmail.com>

Author: Dennis-Mircea

framework-docs/modules/ROOT/pages/core/beans/java/composing-configuration-classes.adoc

@@ -610,6 +610,19 @@ Kotlin::
 See the {spring-framework-api}/context/annotation/Conditional.html[`@Conditional`]
 javadoc for more detail.
 
+[NOTE]
+====
+A `@Conditional` declared on an enclosing `@Configuration` class gates the
+registration of nested `@Configuration` classes within it only when the
+nested class is reached through the parser's recursion from its enclosing
+class, or through `@Import`. When the nested class is discovered
+independently of its enclosing class, for example via `@ComponentScan` or
+by directly registering it against the application context, it is processed
+using only its own `@Conditional` annotations. In that case, redeclare the
+relevant conditions on the nested class, or extract them into a composed
+annotation applied to both, if the same gating is intended.
+====
+
 
 [[beans-java-combining]]
 == Combining Java and XML Configuration

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

@@ -341,6 +341,18 @@
  * with the {@code @Profile} annotation to provide two options of the same bean to the
  * enclosing {@code @Configuration} class.
  *
+ * <p>{@link Conditional @Conditional} annotations declared on an enclosing
+ * {@code @Configuration} class gate registration of any nested
+ * {@code @Configuration} classes within it when the nested class is reached
+ * through the parser's recursion from its enclosing class (the case shown
+ * above) or via {@link Import @Import}. When the nested class is discovered
+ * independently of its enclosing class, for example via
+ * {@link ComponentScan @ComponentScan} or by directly registering the nested
+ * class against the application context, it is processed using only its own
+ * {@code @Conditional} annotations. In that case, redeclare the relevant
+ * conditions on the nested class, or extract them into a composed
+ * annotation applied to both, if the same gating is intended.
+ *
  * <h2>Configuring lazy initialization</h2>
  *
  * <p>By default, {@code @Bean} methods will be <em>eagerly instantiated</em> at container