for(Iterator i = messageHolders.iterator(); i.hasNext(); )
if (messageHolders == null)
   public String toString()   {      StringBuffer sb = new StringBuffer("SendTransactionRequest[");      for(Iterator i = messageHolders.iterator(); i.hasNext(); )      {         sb.append(((MessageHolder)i.next()).getMessage());         if (i.hasNext())         {            sb.append(',');         }      }      sb.append("]");      return sb.toString();   }