@Override
    public synchronized Throwable fillInStackTrace() {
        // do nothing
        return null;
    }
@Test
    void testFillInStackTrace() {
        SkipCallbackWrapperException skipCallbackWrapperException = new SkipCallbackWrapperException(new Throwable("error"));
        assertNull(skipCallbackWrapperException.fillInStackTrace());

    }