static <T> MultiConverter<T> wrapConverter(final Converter<T> converter) {
            return values -> {
                if (NullSafe.isEmptyCollection(values)) {
                    return Collections.emptyList();
                } else {
                    return values.stream()
                            .filter(val -> !NullSafe.isBlankString(val))
                            .map(converter::apply)
                            .filter(Objects::nonNull) // Null items would NPE on Collectors.toList
                            .toList();
                }
            };
        }
Wraps a one to one {@link Converter} function inside a {@link MultiConverter}.
stroom-db-util/src/main/java/stroom/db/util/ExpressionMapper.java