The method is derived from here.
The source code is derived from here.
But do not support Blender 2.80b.
In the last step, you should set the path mappings to blender addon path. Or config the pycharm project to addon path. On my windows10 system, it's C:\Users\zhuc\AppData\Roaming\Blender Foundation\Blender\2.80\scripts\addons.
auto-complete can reference here