Was the Museum built without union labor?

Many people believe that the National Civil Rights Museum is built on dubious foundations. It has been alleged from several sources, that the construction of the site itself was built using non-union labor. If this is true, it really would be a national disgrace as Dr. King's sole purpose in visiting the Lorraine Motel was to lend support to the Sanitation Workers Union in Memphis during their strike. Can it be that so little has been learned?