code: public void migrateTo( JournalQueue otherQueue )
      {
          if (head == null)
              return; // Empty
          
          if (otherQueue.head == null)
          {
              // Other queue was empty, copy everything
              otherQueue.head = head;
              otherQueue.tail = tail;
              otherQueue.size = size;
          }
          else
          {
              // Other queue is not empty, append operations
              otherQueue.tail.setNext(head);
              otherQueue.tail = tail;
              otherQueue.size += size;
          }
          
          // Clear this queue
          head = tail = null;
          size = 0;
      }
docs: Migrate all operations to the given target queue
  @param otherQueue target journal queue