Generate configuration metadata for records

Update `spring-boot-configuration-processor` to support generating
configuration metadata from record parameter javadoc.

See gh-29403

spring-boot-project/spring-boot-docs/src/docs/antora/modules/reference/pages/features/developing-auto-configuration.adoc

@@ -255,6 +255,8 @@ include-code::AcmeProperties[]
 
 NOTE: You should only use plain text with `@ConfigurationProperties` field Javadoc, since they are not processed before being added to the JSON.
 
+If you use `@ConfigurationProperties` with record class then record components' descriptions should be provided via class-level Javadoc tag `@param` (there are no explicit instance fields in record classes to put regular field-level Javadocs on).
+
 Here are some rules we follow internally to make sure descriptions are consistent:
 
 * Do not start the description by "The" or "A".

spring-boot-project/spring-boot-docs/src/docs/antora/modules/specification/pages/configuration-metadata/annotation-processor.adoc

@@ -89,6 +89,8 @@ The Javadoc on fields is used to populate the `description` attribute. For insta
 
 NOTE: You should only use plain text with `@ConfigurationProperties` field Javadoc, since they are not processed before being added to the JSON.
 
+If you use `@ConfigurationProperties` with record class then record components' descriptions should be provided via class-level Javadoc tag `@param` (there are no explicit instance fields in record classes to put regular field-level Javadocs on).
+
 The annotation processor applies a number of heuristics to extract the default value from the source model.
 Default values have to be provided statically. In particular, do not refer to a constant defined in another class.
 Also, the annotation processor cannot auto-detect default values for ``Enum``s and ``Collections``s.