public V get(K key) {
		lock.readLock().lock();
		try {
			return rawMap.get(MutableObj.of(key));
		} finally {
			lock.readLock().unlock();
		}
	}
@Test
	public void getConcurrencyTest(){
		final SimpleCache<String, String> cache = new SimpleCache<>();
		final ConcurrencyTester tester = new ConcurrencyTester(9000);
		tester.test(()-> cache.get("aaa", ()-> {
			ThreadUtil.sleep(200);
			return "aaaValue";
		}));

		assertTrue(tester.getInterval() > 0);
		assertEquals("aaaValue", cache.get("aaa"));
		IoUtil.close(tester);
	}