docs: public void verifyMessageSize(int maxMessageSize) {
         Iterator<MessageAndOffset> shallowIter =  internalIterator(true);
         while(shallowIter.hasNext()) {
             MessageAndOffset messageAndOffset = shallowIter.next();
             int payloadSize = messageAndOffset.message.payloadSize();
             if(payloadSize > maxMessageSize) {
                 throw new MessageSizeTooLargeException("payload size of " + payloadSize + " larger than " + maxMessageSize);
             }
         }
      }