The official theme for the 2015 Angel City Jazz Festival is “Listen,” which is a mandate not only for the music but also for the message behind the notes. We find ourselves again in an uneasy time, with hatred and unrest headlining the daily news. While it’s naive to assume music solves every problem, it gives all of us a shared beauty which can inform and unite us against hatred. Flowers can overcome bullets, which is the message percussionist Alex Cline sends with his Flower Garland Orchestra, dedicated to the Vietnamese Zen master and peace activist Thich Nhat Hanh. The teacher, author and poet turns 90 on October 11, which is also the day of Cline’s show, a powerful finale to this year’s festival of remarkable sonic and social impact.