Incidental contact that does not hinder the player from shooting or reaching the basket is not a foul and it is unfortunate that the league has gotten progressively worse at calling a ton of fouls against defenders on popular players where there was only incidental contact. As someone who exclusively watches a star player that benefits from this trend it is no wonder that you see fouls where true basketball fans see incidental contact and great defense. If the Johnson contact had stopeed any of his momentum or Plumlee had jumped forward and made bodily contact with Lebron then I would be on your side of the call; however, in this instance neither of those things happened and you are wrong.