Lombok's lombok.copyableAnnotations not working with Jackson annotations

fugigoose :

I'm trying to make use of Lombok's new copyableAnnotations feature in order to have Jackson annotations like @JsonIgnore and @JsonValue copied to generated getter/wither methods. This blog seems to suggest this should work: https://www.thecuriousdev.org/lombok-builder-with-jackson/. However, when I try this I simply get "error: annotation type not applicable to this kind of declaration" (pointing to my value field). Why is this not working and how do I make it work? Perhaps I'm misunderstanding how this feature is supposed to work. I'm using lombok 1.18.8.

model.java:

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonValue;
import lombok.Value;

import javax.validation.constraints.NotNull;

@Value
public class BrandId implements ValueObject<Long> {

    @JsonCreator
    public static BrandId of(final Long value) {

        return new BrandId(value);
    }

    @NotNull
    @JsonValue
    private Long value;
}

lombok.config:

config.stopBubbling = true

lombok.copyableAnnotations += com.fasterxml.jackson.annotation.JsonIgnore
lombok.copyableAnnotations += com.fasterxml.jackson.annotation.JsonProperty
lombok.copyableAnnotations += com.fasterxml.jackson.annotation.JsonValue

ruakh :

Why is this not working […] ?

The @JsonValue annotation is only allowed on method declarations and on declarations of other annotation types; so, with or without Lombok, you can't put it on a field. (If you look at its Javadoc, you'll see that it's annotated with @Target(value={ANNOTATION_TYPE,METHOD}).)

The good news is that @JsonValue only applies to getter methods (not setter methods, builder methods, etc.), and there can be only one of it per class, so it's not a big deal to just manually create that one getter:

    @NotNull
    private Long value;

    @JsonValue
    public Long getValue() {
        return value;
    }

If you really dislike that, then you can use Lombok's experimental onMethod feature:

    @NotNull
    @Getter(onMethod=@__({@JsonValue}))
    private Long value;

which is equivalent to the above except in being experimental (so it may change or disappear in future versions of Lombok and/or Java).