Parser loses position information for Expression3

Parser.jj features the following code snipped in the Expression3 production:

        if (list1.size() == 1) {
            // interpret as single value or query
            return list1.get(0);
        } 

This is problematic because the span of list1 is not the same as the span of its first element.
This makes it look like the expression parsed does not include the opening and closing parens.
This can be a problem for error reporting tools (but there are other use cases that may be impacted).