public static int size() {
        InternalThreadLocalMap threadLocalMap = InternalThreadLocalMap.getIfSet();
        if (threadLocalMap == null) {
            return 0;
        } else {
            return threadLocalMap.size();
        }
    }
@Test
    void testSize() {
        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!");
        InternalThreadLocal.removeAll();
    }