springboot Allow @DefaultValue to be used in fields

Currently, @DefaultValue is limited to constructor arguments. This prevents auto generating constructor with lombok.

If @DefaultValue can be assigned to fields, immutable properties class can be written like this:

```java @Getter @AllArgsConstructor @ConfigurationProperties(prefix = "my") @ConstructorBinding public class MyProperties {

@DefaultValue("Foo")
private final String name;

}

Comment From: snicoll

I have some sympathy for that but enabling @DefaultValue on field opens up the possibility of the annotation to be used in non-lombok classes and I am not keen to do that.

Thanks for the suggestion anyway.