public String yqlRepresentation() {
        try {
            return yqlRepresentation(true);
        } catch (NullItemException e) {
            return "Query currently a placeholder, parsing is deferred";
        } catch (IllegalArgumentException e) {
            return "Invalid query: " + Exceptions.toMessageString(e);
        } catch (RuntimeException e) {
            return "Unexpected error parsing or serializing query: " + Exceptions.toMessageString(e);
        }
    }
Serialize this query as YQL+. This method will never throw exceptions,
but instead return a human readable error message if a problem occurred while
serializing the query. Hits and offset information will be included if
different from default, while linguistics metadata are not added.

@return a valid YQL+ query string or a human readable error message
@see Query#yqlRepresentation(boolean)
container-search/src/main/java/com/yahoo/search/Query.java