How to deserialize to immutable collection type?

[Nahuel92]

Hi there!

I'm using Java records for my DTOs, which happen to have fields of type List/Map, and I'm trying to enforce immutability. My current DTO looks like:

import com.google.common.collect.ImmutableList;

public record MyDTO(
        @JsonProperty("id") String uuid,
        @JsonProperty("items") @JsonDeserialize(as = ImmutableList.class) List<String> items){
}

But it throws: io.micronaut.core.beans.exceptions.IntrospectionException: No bean introspection available for type [class com.google.common.collect.ImmutableList]. Ensure the class is annotated with io.micronaut.core.annotation.Introspected.

The workaround that I could use is using compact constructors to make the collection immutable, like this:

public record MyDTO(
        @JsonProperty("id") String uuid,
        @JsonProperty("items") List<String> items){
    public MyDTO {
        items = items == null ? List.of() ? items.stream()
                .filter(Objects::nonNull)
                .toList();
    }
}

But I wonder if there is a better approach to achieve immutability, ideally an annotation or an annotation-parameter that doesn't rely on third-party dependencies. I checked the documentation on Micronaut Serialization, and I haven't seen any annotation or configuration to enable this feature.

Any suggestion is appreciated.
Thanks!

[Nahuel92]

I moved this discussion to Micronaut Core, where I found other Serialization discussions too:
micronaut-projects/micronaut-core#11386