“ Whereas, there exists a labor dispute between, on the one hand, employees represented by the International Longshore and Warehouse Union and, on the other hand, employers and the bargaining association of employers who are (1) U.S. and foreign steamship companies operating ships or employed as agents for ships engaged in service to or from the Pacific Coast ports in California, Oregon, and Washington, and (2) stevedore and terminal companies operating at ports in California, Oregon, and Washington ”