Nets center Jarrett Allen returned to the team’s recently reopened practice facility in Brooklyn on Tuesday wearing a face mask. The team opened its facility for voluntary workouts followingGov. Andrew Cuomo’s Sunday announcement that said New York sports teams can hold in-state training camps. “I believe sports that can come back without people in the stadium, without having people in the arena, do it. Do it,” Cuomo said. “Work out the economics if you can. We want you up. We want people to be able to watch sports to the extent people are still staying home. It gives people something to do.”