Unable to set custom converters on HttpHeadersPreparer

When using spring-data Auditing functionality with unnoficial supported types like OffsetDateTime, you could customize all process using property dateTimeProviderRef on EnableJpaAuditing/EnableMongoAuditing.

All works with no problem for @CreatedDate annotation, but problems comes in with @LastModifiedBy annotation.

Problem in concrete is with class org.springframework.data.rest.webmvc.HttpHeadersPreparer and method getLastModifiedInMilliseconds

	private Optional<Long> getLastModifiedInMilliseconds(Object object) {

		return getAuditableBeanWrapper(object)//
				.flatMap(it -> it.getLastModifiedDate())//
				.map(it -> conversionService.convert(it, Date.class))//
				.map(it -> conversionService.convert(it, Instant.class))//
				.map(it -> it.toEpochMilli());
	}

As you can see, conversionService try to convert lastModifiedDate to Date or Instant, the main problem is that conversionService couldn´t be addapted for inclusion of custom converters because it is initilized on HttpHeadersPreparer constructor:

	private final ConfigurableConversionService conversionService = new DefaultConversionService();

	public HttpHeadersPreparer(AuditableBeanWrapperFactory auditableBeanWrapperFactory) {
		Assert.notNull(auditableBeanWrapperFactory, "AuditableBeanWrapperFactory must not be null!");
		Jsr310Converters.getConvertersToRegister().forEach(conversionService::addConverter);
		this.auditableBeanWrapperFactory = auditableBeanWrapperFactory;
	}

It would be nice to reach that conversionService for registering custom converters