@Test
public void nextAvailableKeysNextReturnsNullIfReaderIndexEqualsInitialWriterIndex() {

    // given
    KeySequenceConfig config = createDefaultTestKeySequenceConfig();
    KeySequence sequence = createDefaultTestUUIDSequence(config);
    Iterator<CharSequence> iterator = sequence.nextReaderKeys(1);
    // when
    CharSequence next = iterator.next();
    // then
    assertNull(next);
}