docs: public int compareTo (GTFSError o) {
          if (this.file == null && o.file != null) return -1;
          else if (this.file != null && o.file == null) return 1;
  
          int file = this.file == null && o.file == null ? 0 : String.CASE_INSENSITIVE_ORDER.compare(this.file, o.file);
          if (file != 0) return file;
          int errorType = String.CASE_INSENSITIVE_ORDER.compare(this.errorType, o.errorType);
          if (errorType != 0) return errorType;
          int affectedEntityId = this.affectedEntityId == null && o.affectedEntityId == null ? 0 : String.CASE_INSENSITIVE_ORDER.compare(this.affectedEntityId, o.affectedEntityId);
          if (affectedEntityId != 0) return affectedEntityId;
          else return Long.compare(this.line, o.line);
      }