public T getValue() {
        return this.value;
    }
@Test
    @SuppressWarnings("unchecked")
    void testValue() {
        Pane<LongAdder> pane = mock(Pane.class);
        LongAdder count = new LongAdder();
        when(pane.getValue()).thenReturn(count);
        assertEquals(count, pane.getValue());
        when(pane.getValue()).thenReturn(null);
        assertNotEquals(count, pane.getValue());
    }