That (within the context of the question) tells you what happens once you know that an attack is already being skipped due to Forcefield, it does not address whether a damage barrier attack will trigger Forcefield. Put another way, the text you're referring to just says that if a Forcemaster has Circle of Lightning and Forcefield on, a creature attacks her in melee, and the attack is avoided due to the Forcefield, that creature won't get hit by the damage barrier attack from Circle of Lightning. It does not describe whether the Forcemaster will get hit by damage barriers when she makes melee attacks and has an active Forcefield enchanting her.