(patent validity case involving varieties of grapevines patented under PVPA; patents owned by USDA, but paid for by defendant which is funded by taxes levied on growers of table grapes; to buy patented varieties from nurseries, growers had to sign “Domestic Grower’s License Agreement” which barred growers from propagating the plants and allowed defendant to void agreement and order destruction of plants if agreement violated; plaintiff, grower, challenged validity and enforceability of patents; complaint allowed to be amended to add claims for rescission/restitution and unjust enrichment).