@Test
public void testGetSha1OrNull() throws IOException {

    // for a contentSource that doesn't specify the sha1
    assertNull(contentSource.getSha1OrNull());
    // for a contentSource that *does* specify the sha1
    final B2ContentSource withSha1 = B2FileContentSource
            .builder(file)
            .setSha1(SAMPLE_SHA1)
            .build();
    assertEquals(SAMPLE_SHA1, withSha1.getSha1OrNull());
}