BLACKPINK's Jennie performed as a headliner at Denmark's Roskilde Festival and Poland's Open'er Festival over the weekend, becoming the first K-pop solo artist to headline two major European music festivals back-to-back, her agency said Monday. The singer performed her hits, including "Mantra," "ExtraL," "Starlight" and "Like Jennie," appearing at the music festivals on Friday and Saturday (local time), respectively, according to OA Entertainment. "Jennie's inclusion reflects current trends and