It should be `"$@"`.

The difference appears when the parameters contain spaces. If the script is called like this: `script.sh A="b c" D=e`, `$@` will be expended to `A=b c D=e`, and the export would result of A=b, c=, D=e. `"$@"` would be expended to `'A=b c' 'D=e'`, and the export would work correctly.