How do you undisable in viewport all object in a collection? I have a complex scene I moved from 2.79 to 2.81. What makes it complex is that it has lots of objects as childs of other objects. Think complex folder tree. Basically hundred folders and each have their own sub folder structure. For whatever reason some objects are randomly disabled in viewport and as such hidden from view and I want to undisable them. Make everything visible. But doing them all individually is just too much work and would be extremely slow. 

Is there a script or some hack or hidden blender feature which allows me to set all objects in one collection visible in viewport? Or even all objects visible in all of the blend file? Going back to 2.79 and re-importing with 2.81 compatible viewport settings is too late at this point.

The title claims this question is subjective but I think this is very much a question which has a solution that works and is not about opinion about something. If I wanted to make an opinion I'd say the migration of assets from 2.7x to 2.8x needs more work.
Pressing H will hide the selected objects from viewport, Alt+H will unhide all objects in viewport.

You can also right-click the collection in the Outliner, and select Visibility > Show All Inside