Document @ConfigurationPropertiesBinding should use static bean methods

Closes gh-45621

Author: philwebb

spring-boot-project/spring-boot-docs/src/docs/antora/modules/reference/pages/features/external-config.adoc

@@ -1137,9 +1137,15 @@ NOTE: The preceding merging rules apply to properties from all property sources,
 Spring Boot attempts to coerce the external application properties to the right type when it binds to the javadoc:org.springframework.boot.context.properties.ConfigurationProperties[format=annotation] beans.
 If you need custom type conversion, you can provide a javadoc:org.springframework.core.convert.ConversionService[] bean (with a bean named `conversionService`) or custom property editors (through a javadoc:org.springframework.beans.factory.config.CustomEditorConfigurer[] bean) or custom converters (with bean definitions annotated as javadoc:org.springframework.boot.context.properties.ConfigurationPropertiesBinding[format=annotation]).
 
-NOTE: As this bean is requested very early during the application lifecycle, make sure to limit the dependencies that your javadoc:org.springframework.core.convert.ConversionService[] is using.
+[NOTE]
+====
+Beans used for property conversion are requested very early during the application lifecycle so make sure to limit the dependencies that your javadoc:org.springframework.core.convert.ConversionService[] is using.
 Typically, any dependency that you require may not be fully initialized at creation time.
-You may want to rename your custom javadoc:org.springframework.core.convert.ConversionService[] if it is not required for configuration keys coercion and only rely on custom converters qualified with javadoc:org.springframework.boot.context.properties.ConfigurationPropertiesBinding[format=annotation].
+
+You should also declare any javadoc:org.springframework.boot.context.properties.ConfigurationProperties[format=annotation] beans using `static` methods to avoid "`bean is not eligible for getting processed by all BeanPostProcessors`" warnings.
+====
+
+TIP: You may want to rename your custom javadoc:org.springframework.core.convert.ConversionService[] if it is not required for configuration keys coercion and only rely on custom converters qualified with javadoc:org.springframework.boot.context.properties.ConfigurationPropertiesBinding[format=annotation].
 
 
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationProperties.java

@@ -37,6 +37,10 @@
  * <p>
  * Note that contrary to {@code @Value}, SpEL expressions are not evaluated since property
  * values are externalized.
+ * <p>
+ * Static methods should be used when declaring {@code @ConfigurationProperties} beans to
+ * ensure that "bean is not eligible for getting processed by all BeanPostProcessors"
+ * warnings are not produced.
  *
  * @author Dave Syer
  * @since 1.0.0