public short getReplicas() {
    return replicas == null ? DEFAULT_REPLICAS : replicas;
  }
@Test
  public void shouldDefaultIfNoReplicasSupplied() {
    // Given:
    // When:
    final TopicProperties properties = new Builder()
        .withName("name")
        .withWithClause(Optional.empty(), Optional.of(1), Optional.empty(), Optional.of((long) 100))
        .build();

    // Then:
    assertThat(properties.getReplicas(), is(TopicProperties.DEFAULT_REPLICAS));
  }