static Set<Integer> parseStatusCodes(String statusCodesString) {
    if (statusCodesString == null || statusCodesString.isEmpty()) {
      return Collections.emptySet();
    }
    Set<Integer> codes = new LinkedHashSet<Integer>();
    for (String codeString : statusCodesString.split(",")) {
      codes.add(Integer.parseInt(codeString));
    }
    return codes;
  }
@Test
  void parseCodes() {
    assertThat(LBClient.parseStatusCodes("")).isEmpty();
    assertThat(LBClient.parseStatusCodes(null)).isEmpty();
    assertThat(LBClient.parseStatusCodes("504")).contains(504);
    assertThat(LBClient.parseStatusCodes("503,504")).contains(503, 504);
  }