char expectChars(char expected1, char expected2) {
            if (!valid()) {
                throw new IllegalInputException("Expected '" + expected1 + "' or '" + expected2 +"', end of spec reached at " + spec());
            }
            var act = peek();
            if (act != expected1 && act != expected2) {
                throw new IllegalInputException("Expected '" + expected1 + "' or '" + expected2 + "', got '" + act + "' at " + spec());
            }
            step();
            return act;
        }
Decide if sortorder is ascending or not.
container-search/src/main/java/com/yahoo/search/query/Sorting.java