HOMESTEAD, Fla. — U.S. officials provided a glimpse Friday into a South Florida facility housing more than 1,000 teenage migrants, seeking to dispel any suggestions that children are being mistreated. Private contractors who run the Homestead Temporary Shelter for Unaccompanied Children, about 25 miles southwest of Miami, showed journalists around the campus-like complex for about an hour. Journalists were not permitted to interview the children, and no cameras or recorders of any kind were allowed inside. The tour included dorm-style buildings where children sleep up to 12 per room in steel-framed bunk beds, and warehouse-sized, air-conditioned white tents where minors attend classes and watch movies. Boys and girls, mostly kept separate, could be seen walking in line to the dining hall and classes, wearing government-issued cotton T-shirts and gym shorts.