Merge pull request #29276 from mihailcornescu

* pr/29276:
  Polish "Add a note on early init with @ConditionalOnExpression"
  Add a note on early init with @ConditionalOnExpression

Closes gh-29276

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/ConditionalOnExpression.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -27,6 +27,11 @@
 /**
  * Configuration annotation for a conditional element that depends on the value of a SpEL
  * expression.
+ * <p>
+ * Referencing a bean in the expression will cause that bean to be initialized very early
+ * in context refresh processing. As a result, the bean won't be eligible for
+ * post-processing (such as configuration properties binding) and its state may be
+ * incomplete.
  *
  * @author Dave Syer
  * @since 1.0.0

spring-boot-project/spring-boot-docs/src/docs/asciidoc/features/developing-auto-configuration.adoc

@@ -143,6 +143,9 @@ This condition will not match for applications that are run with an embedded ser
 ==== SpEL Expression Conditions
 The `@ConditionalOnExpression` annotation lets configuration be included based on the result of a {spring-framework-docs}/core.html#expressions[SpEL expression].
 
+NOTE: Referencing a bean in the expression will cause that bean to be initialized very early in context refresh processing.
+As a result, the bean won't be eligible for post-processing (such as configuration properties binding) and its state may be incomplete.
+
 
 
 [[features.developing-auto-configuration.testing]]