@ConfigurationProperties: Default value in bound class

You shouldn’t mix @Value and @ConfigurationProperties in the same class. If you want to have default values in a @ConfigurationProperties-annotated class, you can configure the fields with a default value:

@ConfigurationProperties("foo")
public class FooConfig {

    private Integer iterations = 999;

    // getter / setter

}

This change brings with it the added benefit of including the default value in the metadata that’s generated by spring-boot-configuration-processor. The metadata is used by your IDE to provide auto-completion when you’re editing application.properties and application.yaml files.

Lastly, and not directly related to your problem, a @ConfigurationProperties-annotated class should not be annotated with @Configuration. An @Configuration-annotated class is used to configure beans via @Bean methods. Your FooConfig class should either be annotated with @Component or you should use @EnableConfigurationProperties(FooConfig.class) on the @Configuration class that wants to use FooConfig.