During a packed night at Blake Shelton’s Oklahoma bar, the crowd expected a set list of old favorites, but instead, they got an unexpected moment. Blake Shelton stepped up to the microphone and called out, “Zuma, come here.” Gwen Stefani’s 14-year-old son took the stage, picked up his guitar, and sang the first verse of “God’s Country” and the crowd erupted. Gwen, standing in the back, wiped away tears as her son officially stepped into the spotlight…