Force Milliseconds When Serializing Instant to ISO8601 using Jackson

Question

I have some questions related to JSON serialization using Jackson in a project where I use Spring Boot 2.0.0.M6, Spring Framework 5.0.1.R

Answer 1

None of two workarounds mentioned by Sean Carroll works me. I end up with writing my own serializer for Instant.

final ObjectMapper mapper = new ObjectMapper();
final JavaTimeModule javaTimeModule = new JavaTimeModule();
javaTimeModule.addSerializer(Instant.class, new KeepMillisecondInstantSerializer());
mapper.registerModule(javaTimeModule);

public class KeepMillisecondInstantSerializer extends JsonSerializer {

    private final DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSX")
            .withZone(ZoneId.of("UTC"));

    @Override
    public void serialize(final Instant instant, final JsonGenerator jsonGenerator, final SerializerProvider serializerProvider) throws IOException {
        final String serializedInstant = dateTimeFormatter.format(instant);
        jsonGenerator.writeString(serializedInstant);
    }
}

I guess Jackson use Instant.toString() method to serialize Instant objects by default. I also find some discussions about Instant.toString() method on StackOverflow.