joshua is a contractor that agrees to build a new commercial office building in downtown santa barbara. he begins construction on the building but quickly discovers that he did not purchase the correct amount of steel or aluminum to complete the project. joshua asks the owners of the building for more money to cover these additional costs, but the building owners refuse. as a result, joshua stops working, having only completed 30% of the building. if the owners of the building sue joshua, what is their best argument?