apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/config/BizConfig.java/BizConfig/grayReleaseRuleScanInterval
class BizConfig:  public int grayReleaseRuleScanInterval() {
    int interval = getIntProperty("apollo.gray-release-rule-scan.interval", DEFAULT_GRAY_RELEASE_RULE_SCAN_INTERVAL);
    return checkInt(interval, 1, Integer.MAX_VALUE, DEFAULT_GRAY_RELEASE_RULE_SCAN_INTERVAL);
  }