The activewear brand Lululemon has apologised after a promotional event held on the Great Wall of China appeared to mistakenly feature a Japanese drum, prompting an uproar. The Canadian-headquartered company, known for its upmarket leggings, has been growing rapidly in China and arranged for a yoga festival to take place in late May on a section of the wall near Beijing. More than 2,000 people were invited to take part in the event, which was advertised as promoting Chinese culture and wellness, according to the Chinese state-run tabloid Global Times,…