• Map<String, String>

application.yml:

asimiotech:
  layouts:
    default: layouts/default/main
    acme: layouts/acme/main

Spring Boot Configuration Class:

@Configuration
@EnableConfigurationProperties
public class AppConfig {

  @Bean
  @ConfigurationProperties("asimiotech.layouts")
  public Map<String, String> layouts() {
    return new HashMap<>();
  }

// ...
}

Spring Bean Java Class:

@RequiredArgsConstructor
public class SpringBean {

  private final Map<String, String> layouts;

// ...
}

or

public class SpringBean {

  @Autowired
  private Map<String, String> layouts;

// ...
}