This is regular expression. ? makes the pattern in () optional. To explain it further, if you use "?", all paths under /content are valid(including /content as well) but if you dont use "?" then "/content" is not allowed.
This is regular expression. ? makes the pattern in () optional. To explain it further, if you use "?", all paths under /content are valid(including /content as well) but if you dont use "?" then "/content" is not allowed.