If you want to change the format for all dates you can add a builder customizer. Here is an example of a bean that converts dates to ISO 8601:
@Bean
public Jackson2ObjectMapperBuilderCustomizer jsonCustomizer() {
return new Jackson2ObjectMapperBuilderCustomizer() {
@Override
public void customize(Jackson2ObjectMapperBuilder builder) {
builder.dateFormat(new ISO8601DateFormat());
}
};
}