Backlash against the NBA sparked by a tweet in support of Hong Kong protesters shows how tricky it is to do business in China—and the difficult line companies must tread. More from the Wall Street Journal: Visit WSJ.com: http://www.wsj.com Visit the WSJ Video Center: https://wsj.com/video On Facebook: https://www.facebook.com/pg/wsj/videos/ On Twitter: https://twitter.com/WSJ On Snapchat: https://on.wsj.com/2ratjSM Photo Continue Reading…