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!

[dstepanov]

For Micronaut Serialization, you can define custom deserializers/serializers or use @JsonDeserialize(as or @SerdeConfig(deserAs

[Nahuel92]

Hi dstepanov!
Yes, I tried with @JsonDeserialize(as=...) but it didn't work. I'll try with @SerdeConfig and will update if it works that way. Thanks!

[Nahuel92]

I ended up solving my issue by annotating my collection fields with either:

• @Serdeable.Deserializable(as = ImmutableList.class)
• @Serdeable.Deserializable(as = ImmutableMap.class)