code: public void moveTail(int delta) {
  		assert !isRecycled() : "Attempt to use recycled bytebuf";
  		assert tail + delta >= head;
  		assert tail + delta <= array.length;
  		tail += delta;
  	}
docs: Sets new value of {@link #tail} by moving it by the given delta
  if this {@code ByteBuf} is not recycled.
  
  @param delta the value by which current {@link #tail} will be moved.
  New {@link #tail} must be bigger or equal to {@link #head}
  and smaller or equal to the length of the {@link #array}