What are they hiding?

If you are at Paine Field in Everett you will see a large number of Boeing 787s sitting around. They all have their windows and doors covered. But what are they hiding? Seeing as I don't have any contacts at Boeing I will have to guess. Boeing could be using them to hide immigrants, maybe they are letting homeless people live in them and don't want the public seeing cause they are doing it just for the true goodness of the act. Whatever they are doing in these planes, one thing is sure they don't want us to see.