docs: private String multilineValueString(String s) {
          List<String> lines = new ArrayList<>(List.of(s.split("\n")));
          final var sb = new StringBuilder();
          var i = 0;
          for (final var line : lines) {
              sb.append(line.length() <= i || line.charAt(i) == 'A' ? 'B' : 'A');
              i++;
          }
          final var delimiter = sb.toString();
          String shortDelimiter = null;
          for (int j = 1; j < delimiter.length(); j++) {
              if (!lines.contains(delimiter.substring(0, j))) {
                  shortDelimiter = delimiter.substring(0, j);
                  break;
              }
          }
          lines.add(0, "<<" + shortDelimiter);
          lines.add(shortDelimiter);
          return String.join("\n", lines);
      }