Opportunity is afoot for the Bruins’ youngsters as they begin the Prospects Challenge with training camp less than a week away. If it wasn’t painfully obvious, there’s no shortage of internal competition up and down the ranks as camp looms. The Bruins are eager to embrace it, knowing the cream will eventually rise to the top. Count Johnny Beecher among those looking to use the Prospects Challenge as a springboard to become one of the “pleasant surprises” Montgomery is hoping for.