Mix 104.1 announced the lineup for its annual free MixFest show at the Hatch Shell on Sept. 16. The headliners are Kelly Clarkson, “Honey, I’m Good’’ singer Andy Grammer, and Blondie. Yes, Debbie Harry’s Blondie. The band’s 11th album, “Pollinator,’’ was released in May. Acts on last year’s MixFest lineup included OneRepublic and Shaggy. Pictured: Harry (left) and Clarkson.