// alone
    assertNull(segment.removeEntryFromChain(entryOne, entryOne));

    // head
    assertSame(entryOne, segment.removeEntryFromChain(entryTwo, entryTwo));

    // middle
    ReferenceEntry<Object, Object> newFirst = segment.removeEntryFromChain(entryThree, entryTwo);
    assertSame(keyThree, newFirst.getKey());