In A. B. Kirschbaum Co. v. Walling, 316 U.S. 517, 62 S.Ct. 1116, 86 L.Ed. 1638 (1942), decided June 1, 1942, the Supreme Court decided that employees engaged in the maintenance and operation of loft buildings, the tenants of which were engaged principally in the production of goods (clothing) for interstate commerce, were within the coverage of the Act because engaged in an occupation necessary to the production of goods for commerce, within the meaning of Section 3(j) of the Fair Labor Standards Act. The employees in that case included an engineer, fireman, elevator operators, watchmen, and porters. The porters kept the building clean and habitable. In the course of its opinion, the Supreme Court said, at page 524 of 316 U.S., at page 1120 of 62 S.Ct.: "Without light and heat and power the tenants could not engage, as they do, in the production of goods for interstate commerce. The maintenance of a safe, habitable building is indispensable to that activity." The Supreme Court found no requirement in the Act that the employees must themselves participate in the physical process of the making of the goods before they could be regarded as engaged in the production of the goods. At page 524 of 316 U.S., at page 1120 of 62 S.Ct. The court said, at pages 525-526 of 316 U.S., at page 1121 of 62 S.Ct.: "In our judgment, the work of the employees in these cases had such a close and immediate tie with the process of production for commerce, and was therefore so much an essential part of it, that the employees are to be regarded as engaged in an occupation `necessary to the production of goods for commerce'."