@Test
public void testSize() throws InterruptedException {

    final InternalThreadLocal<Integer> internalThreadLocal = new InternalThreadLocal<Integer>();
    internalThreadLocal.set(1);
    Assertions.assertEquals(1, InternalThreadLocal.size(), "size method is wrong!");
    final InternalThreadLocal<String> internalThreadLocalString = new InternalThreadLocal<String>();
    internalThreadLocalString.set("value");
    Assertions.assertEquals(2, InternalThreadLocal.size(), "size method is wrong!");
}