docs: private static String insertStrings(String message, Object[] add) {
  
          StringBuffer sb        = new StringBuffer(message.length() + 32);
          int          lastIndex = 0;
          int          escIndex  = message.length();
  
          // removed test: i < add.length
          // because if mainErrorMessage is equal to "blabla $$"
          // then the statement escIndex = mainErrorMessage.length();
          // is never reached!  ???
          for (int i = 0; i < add.length; i++) {
              escIndex = message.indexOf(MESSAGE_TAG, lastIndex);
  
              if (escIndex == -1) {
                  break;
              }
  
              sb.append(message.substring(lastIndex, escIndex));
              sb.append(add[i] == null ? "null exception message"
                                       : add[i].toString());
  
              lastIndex = escIndex + MESSAGE_TAG.length();
          }
  
          escIndex = message.length();
  
          sb.append(message.substring(lastIndex, escIndex));
  
          return sb.toString();
      }