class CollectionIntegerConverter implements AttributeConverter<Collection<Integer>, String> {

    private static final Logger LOGGER = Logger.getLogger(CollectionIntegerConverter.class);

    public String convertToDatastore(final Collection<Integer> attribute) {
        if (attribute == null) {
            return null;
        }
        final StringBuilder sb = new StringBuilder();
        final Iterator<Integer> iterator = attribute.iterator();
        while (iterator.hasNext()) {
            sb.append(iterator.next());
            if (iterator.hasNext()) {
                sb.append(",");
            }
        }
        return sb.toString();
    }

    public Collection<Integer> convertToAttribute(final String columnValue) {<FILL_FUNCTION_BODY>}
}

        if (columnValue == null || StringUtils.isBlank(columnValue)) {
            return null;
        }
        final Collection<Integer> collection = new ArrayList<>();
        for (String s: columnValue.split(",")) {
            try {
                collection.add(Integer.valueOf(s));
            } catch (NumberFormatException e) {
                LOGGER.warn("Unable to convert value to Integer", e);
            }
        }
        return collection;
    
<no_super_class>