@Test
public void testKeyForSource() {

	Map<String, Object> source = new HashMap<>();
	source.put("a", "a1");
	source.put("b", 5);
	source.put("c", 6);
	Object key = mapper.keyForSource(new TestRowProxy(Index.forLabels("a", "b", "c"), "a1", 5, 6));
	assertTrue(key instanceof Map);
	@SuppressWarnings({ "unchecked", "rawtypes" })
	Map<String, Object> keyMap = (Map) key;
	assertEquals(2, keyMap.size());
	assertEquals("a1", keyMap.get("a"));
	assertEquals(5, keyMap.get("b"));
}