@Test
public void returnsNullReaderKeyIfReaderKeyEqualsInitialWriterKey() {

    // given
    KeySequenceConfig config = createDefaultTestKeySequenceConfig();
    KeySequence sequence = createDefaultTestUUIDSequence(config);
    // when
    CharSequence readerKey1 = sequence.nextReaderKey();
    // then
    assertNull(readerKey1);
}