docs: public static String join(String joinChar, String... args) {
          String next = ""; //$NON-NLS-1$
          StringBuilder result = new StringBuilder(length(args) + (args.length - 1));
  
          for (String arg : args) {
              result.append(next);
              result.append(arg);
              next = joinChar;
          }
          return result.toString();
      }