@JsonIgnore
  public Set<String> getGatewaySenderIdsAsSet() {
    if (gatewaySenderIds == null) {
      return null;
    }
    return Arrays.stream(gatewaySenderIds.split(","))
        .filter(StringUtils::isNotBlank)
        .collect(Collectors.toSet());
  }
turn the comma separated ids into a set of id

@return a set of gatewaySenderIds
geode-core/src/main/java/org/apache/geode/cache/configuration/RegionAttributesType.java