class AtLeastOneFieldPresenceConstraint implements Constraint {

    @Override
    public boolean evaluate(Schema schema, JsonNode node) {
        long fieldsPresent = ImmutableList.copyOf(node.fieldNames())
                .stream()
                .filter(fieldNames::contains)
                .count();

        return fieldsPresent >= 1;
    }

      AtLeastOneFieldPresenceConstraint(String... fieldNames);

}