AttributeConverter, how to handle attributeValueType that is either List or String?

[dailytabs]

My source DB is not very normalized. Sometimes I get "string | string | string" and other times I get a list of strings. How do I handle this?

I first tried using a setter with an Object arg, but the setter was never called. So, I created an AttributeConverter implementation and got stuck on what to return for attributeValueType() - it only works half the time, the rest the field is ignored and the data is lost.

[dailytabs]

It is a read only table, so this appears to work. The "half the time" must have been something else...

    public static class MyConverter implements AttributeConverter<List<String>> {
        @Override
        public AttributeValue transformFrom(List<String> input) {
            return AttributeValue.fromL(input.stream().map(AttributeValue::fromS).collect(Collectors.toList()));
        }

        @Override
        public List<String> transformTo(AttributeValue input) {
            if (input.hasL())
                return input.l().stream().map(i -> i.s()).collect(Collectors.toList());
            else
                return Arrays.stream(input.s().split("\\|")).map(String::trim).collect(Collectors.toList());
        }

        @Override
        public EnhancedType<List<String>> type() {
            return EnhancedType.listOf(String.class);
        }

        @Override
        public AttributeValueType attributeValueType() {
            return AttributeValueType.L;
        }
    }