Construct @ConfigurationProperties programmatically

Spring Boot exposes org.springframework.boot.context.properties.bind.Binder, which you can use like this:

import org.springframework.boot.context.event.ApplicationPreparedEvent;
import org.springframework.boot.context.properties.bind.Binder;
import org.springframework.boot.context.properties.source.ConfigurationPropertySources;
import org.springframework.context.ApplicationListener;
import org.springframework.core.env.ConfigurableEnvironment;
public class MyApplicationPreparedListener implements ApplicationListener {
    @Override
    public void onApplicationEvent(ApplicationPreparedEvent event) {
        ConfigurableEnvironment env = event.getApplicationContext().getEnvironment();
        Binder binder = new Binder(ConfigurationPropertySources.get(env));
        MyComplexConfig config = binder.bind("my.config", MyComplexConfig.class)
                .orElseThrow(() -> new IllegalStateException("Could not bind config"));
        System.out.println("Loaded config:");
        System.out.println("  name: " + config.getName());
        System.out.println("  servers: " + config.getServers());
        System.out.println("  timeout: " + config.getNested().getTimeout());
        System.out.println("  labels: " + config.getNested().getLabels());
    }
}

Lets take a configuration properties file and two YAMLs like this:

import lombok.Getter;
import lombok.Setter;
import java.util.List;
import java.util.Map;
@Getter
@Setter
public class MyComplexConfig {
    private String name;
    private List servers;
    private NestedConfig nested;
    @Getter
    @Setter
    public static class NestedConfig {
        private int timeout;
        private Map labels;
    }
}

application.yaml

my:
  config:
    name: DefaultConfig
    servers:
      - default1.server.com
      - default2.server.com
    nested:
      timeout: 30
      labels:
        env: prod
        region: us-east

application-dev.yaml

my:
  config:
    name: DevConfig
    servers:
      - dev1.server.local
    nested:
      timeout: 10
      labels:
        env: dev
        debug: true

SpringBootApplication class:

import com.example.MyApplicationPreparedListener;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
@SpringBootApplication
public class ExampleApplication {
    public static void main(String[] args) {
        new SpringApplicationBuilder(ExampleApplication.class)
                .profiles("dev") // remove it to run with default profile
                .listeners(new MyApplicationPreparedListener()) 
                .run(args);
    }
}

Output for default profile:

Loaded config:
  name: DefaultConfig
  servers: [default1.server.com, default2.server.com]
  timeout: 30
  labels: {env=prod, region=us-east}

Output for dev profile:

Loaded config:
  name: DevConfig
  servers: [dev1.server.local]
  timeout: 10
  labels: {env=dev, debug=true, region=us-east}