code: public org.grails.datastore.mapping.query.api.Criteria order(String propertyName) {
          if (criteria == null) {
              throwRuntimeException(new IllegalArgumentException("Call to [order] with propertyName [" +
                      propertyName + "]not allowed here."));
          }
          propertyName = calculatePropertyName(propertyName);
          Order o = Order.asc(propertyName);
          addOrderInternal(this.criteria, o);
          return this;
      }
docs: Orders by the specified property name (defaults to ascending)
  
  @param propertyName The property name to order by
  @return A Order instance