'Patriots governing Hong Kong': What and why

Can someone who won't support their own country win public office? It's not likely, based on practices around the world.
Most countries and regions examine the qualifications of their candidates and have some requirements to ensure candidates running for public office will uphold their jurisdiction's basic laws.
In China, the concept of "patriots governing Hong Kong" was first put forward by former leader Deng Xiaoping in 1984. Let's have a look at what the phrase means and why it still matters today.