sentence: he has collaborated with such artists as seal , sarah brightman , josh groban , john legend , bebe winans , gladys knight , jessica simpson , shaffer '' ne-yo '' smith , skylar grey , mozella , sacha skarbek , randy jackson , dj khalil , carole bayer sager , jc chasez , fergie , kardinal offishall , bc jean , planet vi , boi-1da , as a songwriter , musician and producer .