Eu estou tentando usar um conversor personalizado com spring-data-mongodb. Eu quero criá-lo por meio de programação, mas recebo o seguinte erro:

org.springframework.core.convert.ConverterNotFoundException: No converter found capable of     converting from type org.joda.time.LocalDate to type java.lang.String
at org.springframework.core.convert.support.GenericConversionService.handleConverterNotFound(GenericConversionService.java:475)
at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:175)
at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:154)
....
....

Segue-se o fragmento de código em falha:

    Mongo mongo = new Mongo();
    MongoDbFactory mongoDbFactory = new SimpleMongoDbFactory(mongo, "database");

    List<Converter> converters = new ArrayList<>();
    converters.add(new LocalDateWriteConverter());
    converters.add(new LocalDateReadConverter());
    CustomConversions customConversions = new CustomConversions(converters);

    MappingContext mappingContext = new SimpleMongoMappingContext();
    MappingMongoConverter mappingMongoConverter = new MappingMongoConverter(mongoDbFactory, mappingContext);
    mappingMongoConverter.setCustomConversions(customConversions);

    MongoTemplate mongoTemplate = new MongoTemplate(mongoDbFactory, mappingMongoConverter);

    MongoDbEvent mongoEvent = new MongoDbEvent(new LocalDate(2012, 12, 8));
    mongoTemplate.insert(mongoEvent);

E aqui estão minhas classes de conversores:

class LocalDateReadConverter implements Converter<String, LocalDate> {
    @Override
    public LocalDate convert(String s) {
        // Conversion code omitted.
    }
}

class LocalDateWriteConverter implements Converter<LocalDate, String> {

    @Override
    public String convert(LocalDate localDate) {
        // Conversion code omitted.
    }
}

A classe que estou tentando persistir é assim:

import org.joda.time.LocalDate;

public class MongoDbEvent {

    private String id;
    private LocalDate date;

    public MongoDbEvent(LocalDate date) {
        this.date = date;
    }

    public String getId() {
        return id;
    }

    public LocalDate getDate() {
        return date;
    }

    @Override
    public String toString() {
        return "MongoDbEvent{" +
                "id='" + id + '\'' +
                ", date=" + date +
                '}';
        }
}