apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/message/ReleaseMessageScanner.java/ReleaseMessageScanner/recordMissingReleaseMessageIds
class ReleaseMessageScanner:  private void recordMissingReleaseMessageIds(List<ReleaseMessage> messages, long startId) {
    for (ReleaseMessage message : messages) {
      long currentId = message.getId();
      if (currentId - startId > 1) {
        for (long i = startId + 1; i < currentId; i++) {
          missingReleaseMessages.putIfAbsent(i, 1);
        }
      }
      startId = currentId;
    }
  }