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.
American Idol American Idol is an American singing competition television series created by Simon Fuller, produced by FremantleMedia North America and 19 Entertainment, and distributed by FremantleMedia North America. It began airing on Fox on June 11, 2002, and ended its first-run on April 7, 2016. In 2018, the show will make its debut on ABC. It started off as an addition to the "Idols" format based on the British series "Pop Idol", and became one of the most successful shows in the history of American television. The concept of the series involves discovering recording stars from unsigned singing talents, with the winner determined by the viewers in America through telephones, Internet, and SMS text voting. Winners chosen by viewers in its fifteen seasons were Kelly Clarkson, Ruben Studdard, Fantasia, Carrie Underwood, Taylor Hicks, Jordin Sparks, David Cook, Kris Allen, Lee DeWyze, Scotty McCreery, Phillip Phillips, Candice Glover, Caleb Johnson, Nick Fradiani, and Trent Harmon.