Disabling WRITE_DATES_AS_TIMESTAMPS not working?

According to the /datetime/ summary, java.time.offsetDateTime objects should serialize out to ISO-8601 strings simply by disabling the SerializationFeature#WRITE_DATES_AS_TIMESTAMPS feature?

I’ve tried to do this in two different ways in the JacksonConfig class:

ObjectMapper mapper = new ObjectMapper()
            .registerModule(new ParameterNamesModule())
            .registerModule(new Jdk8Module())
            .registerModule(new JavaTimeModule())
            .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);

@Bean
@Primary
public ObjectMapper objectMapper(Jackson2ObjectMapperBuilder builder) {
        ObjectMapper objectMapper = builder.createXmlMapper(false).build();
        objectMapper
                .registerModule(new ParameterNamesModule())
                .registerModule(new Jdk8Module())
                .registerModule(new JavaTimeModule())
                .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
        return objectMapper;
}

In both cases, serialized offsetDateTime objects continue to be printed in nanosecond timestamp format (i.e. “expiresOn”:1486138656.853000000).

Only by actually declaring @JsonFormat can I get them to print out in ISO-8601 string.

Is anyone else having this issue?

[cogito-abhijeet]

If you are using swagger with spring boot and your date is Date is always getting serialised as long, 
and SerializationFeature.WRITE_DATES_AS_TIMESTAMPS & spring.jackson.serialization.write-dates-as-timestamps=false are not helping, below solution worked for me. Add it to your class annotated with @SpringBootApplication:

@Autowired
private RequestMappingHandlerAdapter handlerAdapter;

@EventListener
public void handleContextRefresh(ContextRefreshedEvent event) {
    handlerAdapter
            .getMessageConverters()
            .stream()
            .forEach(c -> {
                if (c instanceof MappingJackson2HttpMessageConverter) {
                    MappingJackson2HttpMessageConverter jsonMessageConverter = (MappingJackson2HttpMessageConverter) c;
                    ObjectMapper objectMapper = jsonMessageConverter.getObjectMapper();
                    objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
                }
            });
}

Actual issue: SerializationFeature.WRITE_DATES_AS_TIMESTAMPS value is not read from spring configuration file which need to be set false in order 
to covert long value while serialisation.

[Dienry]

Where do you put this in your code?

ObjectMapper mapper = new ObjectMapper() .registerModule(new ParameterNamesModule()) .registerModule(new Jdk8Module()) .registerModule(new JavaTimeModule()) .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);

Thanks!