public IndexConfig setAttributes(List<String> attributes) {
        checkNotNull(attributes, "Index attributes cannot be null.");

        this.attributes = new ArrayList<>(attributes.size());

        for (String attribute : attributes) {
            addAttribute(attribute);
        }

        return this;
    }
@Test(expected = IllegalArgumentException.class)
    public void testAttributeEmpty() {
        new IndexConfig().setAttributes(Collections.singletonList(""));
    }