docs: public DateTimeFormatterBuilder append(DateTimePrinter printer, DateTimeParser[] parsers) {
          if (printer != null) {
              checkPrinter(printer);
          }
          if (parsers == null) {
              throw new IllegalArgumentException("No parsers supplied");
          }
          int length = parsers.length;
          if (length == 1) {
              if (parsers[0] == null) {
                  throw new IllegalArgumentException("No parser supplied");
              }
              return append0(DateTimePrinterInternalPrinter.of(printer), DateTimeParserInternalParser.of(parsers[0]));
          }
  
          InternalParser[] copyOfParsers = new InternalParser[length];
          int i;
          for (i = 0; i < length - 1; i++) {
              if ((copyOfParsers[i] = DateTimeParserInternalParser.of(parsers[i])) == null) {
                  throw new IllegalArgumentException("Incomplete parser array");
              }
          }
          copyOfParsers[i] = DateTimeParserInternalParser.of(parsers[i]);
  
          return append0(DateTimePrinterInternalPrinter.of(printer), new MatchingParser(copyOfParsers));
      }