static boolean isNull(final Val val) {
        return val == null
                || val == ValNull.INSTANCE
                || Objects.equals(ValNull.INSTANCE, val)
                || val.type().isNull();
    }
Creates a Val in a null safe way, either returning {@link ValNull} or the product
of the {@code creator} function.
stroom-query/stroom-query-language/src/main/java/stroom/query/language/functions/Val.java