Using a custom interceptor in spring-boot, the @Value default is taking precedence over my configured value

Question

I am in the trenches of writing my first spring-boot app, so I believe I have a configuration issue somewhere that is causing my error.

I have a class, "MyInterceptor", and it is annotated with "@Component" and extending HandlerInterceptorAdapter.

@Component
public class MyInterceptor extends HandlerInterceptorAdapter { ... }

And I have a configuration class "WebConfiguration" that is annotated with "@Configuration" (and is NOT annotated with "@EnableWebMvc").

I declare/inject my interceptor class in WebConfiguration like so:

@Resource
private MyInterceptor myInterceptor;

and then specify this class as an interceptor like so:

@Override
public void addInterceptors(InterceptorRegistry registry) {
    registry.addInterceptor(myInterceptor);
}

In MyInterceptor, I have a property declared for which I want to inject a value. I have it declared, with a default, like so:

@Value("${my.interceptor.property:default_value}")
private String myInterceptorProperty;

When I have the "default_value" declared in the @Value annotation as I do above, then that value is always used. The value declared in my application-dev.yml file is ignored.

When I remove the default value, then the value in my application-dev.yml is used.

It is my suspicion that the default value from the @Value annotation is being loaded AFTER the configured value and overriding it for some reason. But I can't figure out why or how to stop it.

Other services in my app that are using @Value annotations, but that are NOT declared/injected in my WebConfiguration, are not exhibiting the same behavior.

I tried adding my interceptor like this instead:

@Bean
public MyInterceptor getMyInterceptor() {
    return new MyInterceptor();
}

and then changed this:

@Override
public void addInterceptors(InterceptorRegistry registry) {
    registry.addInterceptor(getMyInterceptor());
}

But when I did this, then the configuration values in the application-dev.yml were never picked up regardless of whether or not I had a default value declared.

I do understand why the @Resource annotated injection is making my configured properties available, and why the direct constructor call in the Config class is not. But is using the @Resource annotation the wrong way to do it? Why isn't my default being overridden?

How should I be injecting configuration values into my interceptors and other classes that are similarly declared in my Config class?