/**
  * Read the next message. 
  * Override the parent method: we don't want to increment the byte offset 
  *
  * @return string Message (raw)
  * @throws Kafka_Exception when the message cannot be read from the stream buffer
  */
 protected function getMessage()
 {
     $msg = parent::getMessage();
     // do not increment the offset for internal iterators
     $this->validByteCount = 0;
     return $msg;
 }