Generate or provide metadata for externally provided configuration properties used with variable prefixes

[cachescrubber]

I use the configuration properties feature to bind properties multiple times using different prefixes which are dynamic in nature.

@ConfigurationProperties(prefix = "client-a")
@Bean
public MyClientProperties clientAproperties() {
  return new  MyClientProperties();
}

@ConfigurationProperties(prefix = "client-b")
@Bean
public MyClientProperties clientBproperties() {
  return new  MyClientProperties();
}

As long as the MyClientProperties class is local to my spring-boot project, the spring-boot-configuration-processor is able to generate metadata for each prefix I use. In particular, the description and defaultValue metatdata is extracted from the field level javadoc of the class:

public class MyClientProperties {
  /**
   * Web service remote endpoint url
   */
  public String endpoint = "http://localhost:8080/services";
...
}

The generated metadata

    {
      "name": "client-a.endpoint",
      "type": "java.lang.String",
      "description": "Web service remote endpoint url",
      "sourceType": "com.example.client.MyClientProperties",
      "defaultValue": "http:\/\/localhost:8080\/services"
    },
...
    {
      "name": "client-b.endpoint",
      "type": "java.lang.String",
      "description": "Web service remote endpoint url",
      "sourceType": "com.example.client.MyClientProperties",
      "defaultValue": "http:\/\/localhost:8080\/services"
    },

This changes as soon as the class is moved to an external jar dependency in order to be shared among several projects and the spring-boot-configuration-processor has no access to the source code of the properties type. The description and defaultValue metadata is no longer available.

    {
      "name": "client-a.endpoint",
      "type": "java.lang.String",
      "sourceType": "com.example.client.MyClientProperties"
    },
...
    {
      "name": "client-b.endpoint",
      "type": "java.lang.String",
      "sourceType": "com.example.client.MyClientProperties"
    },

If MyClientProperties would be used with a fixed prefix only, I could run the spring-boot-configuration-processor within the external jar module and package the generated metatdata.json file. The generated metadata would be visible in the context of the consuming spring-boot application under the my-client prefix.

@@ConfigurationProperties(prefix = "my-client")
public class MyClientProperties {
...
}

What I need is a mechanism to access the description and defaultValue metatdata from the externally provided properties class below the dynamic prefixes chosen by the consuming spring-boot application.

Note: I submited a question at StackOverflow, but in the meantime I think this is most likely an enhancement request.

[cachescrubber]

nested configuration properties are another use-case.

public class MyApplicationProperties {

  @NestedConfigurationProperty
  private MyClientProperties client;

[knoobie]

Please take a look at the official documentation, it's well written there.
Edit: Hint - you have to add the spring-boot-configuration-processor as a optional dependency to your jar containing the configuration

[snicoll]

@knoobie thanks for trying to help but @cachescrubber is trying to generate metadata content from an external jar.

This is effectively a duplicate of #18366

[cachescrubber]

@snicoll Thx. My bad, I missed #18366. I'll update StackOverflow accordingly.