@Test
public void configReturnsACopyOfServerUrisList() {

    // given
    Builder builder = createTestObjectFactoryBuilder();
    builder.withServerUris("http://localhost:9200;http://localhost:9201;http://localhost:9202");
    ClientObjectFactory<TransportClient, BulkRequest> config = builder.build();
    // when
    Collection<String> serverUrisList = config.getServerList();
    serverUrisList.add("test");
    // then
    assertNotEquals(serverUrisList.size(), config.getServerList().size());
}