@Test
public void shouldReturnNullInputStream() {

    // given
    when(delegate.get(any())).thenReturn(null);
    ContentCache contentCache = new ZippedContentCache(delegate);
    // when
    final InputStream stream = contentCache.get(() -> StringUtils.EMPTY);
    // then
    verify(delegate, times(1)).get(any());
    assertNull(stream);
}