By Juliette Jabkhiro and LEA GUEDJ PARIS (Reuters) – When police came knocking on the door of his eastern Paris home on July 16, 1942, 15-year-old French Jew Joseph Schwartz was no longer there. Forewarned, he and his father Lejbus had gone into hiding. He had assumed his mother Ruchla and younger brother Paul would be safe – the few roundups of Jews that had already taken place had only targeted men. But the authorities had widened the net. That day and the next, entire families were snatched from their homes in the largest mass detention of Jewish people by French police in collaboration wit…