What singer made appearances during Keith Urban's Ripcord World Tour who also the winner of the  fourth season of "American Idol"?
Ripcord World Tour The Ripcord World Tour (stylized as the ripCORD World Tour) was the eleventh concert tour by Australian singer Keith Urban. The tour was in support of his tenth studio album "Ripcord" (2016). The tour began on 2 June 2016 in Bonner Springs, Kansas and concluded on 17 December 2016 with two shows in Brisbane, Australia. Brett Eldredge, Maren Morris and Dallas Smith were supporting acts for Urban in North America. The Oceania leg of the tour was co-headlined with American singer Carrie Underwood, with Buchanan as opening act.
Australian Idol (season 7) The seventh and final season of the "Australian Idol" series began on 9 August 2009, to determine who would succeed Season 6 winner, Wes Carr. Beginning amid controversy, judge Kyle Sandilands was replaced by Sony Music record executive, Jay Dee Springbett. It was the first season where all four final contestants were eighteen years old or younger. Stan Walker was declared the winner on 22 November 2009.