code: public void tail(int pos) {
  		assert !isRecycled() : "Attempt to use recycled bytebuf";
  		assert pos >= head && pos <= array.length;
  		tail = pos;
  	}
docs: Sets {@link #tail} if this {@code ByteBuf} is not recycled.
  
  @param pos the value which will be assigned to the {@link #tail}.
  Must be bigger or equal to {@link #head}
  and smaller than length of the {@link #array}