public String getSystemOffsetDefault(String systemName) {
    // first check stream system default
    String systemOffsetDefault = get(String.format("systems.%s.default.stream.samza.offset.default", systemName));

    // if not set, check the deprecated setting
    if (StringUtils.isBlank(systemOffsetDefault)) {
      systemOffsetDefault = get(String.format("systems.%s.samza.offset.default", systemName));
      if (StringUtils.isBlank(systemOffsetDefault)) {
        return SAMZA_SYSTEM_OFFSET_UPCOMING;
      }
    }

    return systemOffsetDefault;
  }
Get system offset default value.
systems.'system'.default.stream.samza.offset.default is the config.
systems.'system'.samza.offset.default is the deprecated setting, but needs to be checked for backward compatibility.
@param systemName get config value for this system.
@return value of system reset or default ("upcoming") if none set.
samza-core/src/main/java/org/apache/samza/config/SystemConfig.java