Are Jews with Germanic/Ashkenazi names German ethnically?

It's historically very difficult to "place" Jewish ancestry because throughout European history, Jewish communities have been shuffled around and forced away from homes they may have had for generations. Sometimes it was because an area was suffering a plague and blamed the Jews. Sometimes it was accusations of witchcraft. Sometimes it was just something to do. Surnames are also difficult to trace in certain areas because they weren't used. Avram was the son of Motl the Butcher and that's all anyone needed to identify him. When surnames became mandatory in Eastern Europe, many of them were sold. Wealthy families could afford "good" surnames that honored the heroes of the Jewish past. Poor Jews were often igned mocking surnames to remind them how put down they were. Goldwater (Goldwer) is the first one that comes to mind because it literally means "urine."