title: Flowable 6, how to get comand context
body: <p>I am a newbie to Flowable 6, when I call Context.getCommandContext(), in some cases it return a null object.</p>
  <p>My question is that which conditions are needed to have a command context?. And in my case, if it is null, can I manually add one. If yes, how to do it?</p>