docs: public static String join(String start, String linePrefix, Collection<?> lines) {
          if (lines.isEmpty()) {
              return "";
          }
          StringBuilder out = new StringBuilder(start);
          for (Object line : lines) {
              out.append(linePrefix).append(line).append("\n");
          }
          return out.substring(0, out.length() - 1); //lose last EOL
      }