code: public CdnPathBuilder preview(int width, int height) {
          dimensionsGuard(width, height);
          sb.append("/-/preview/")
                  .append(width)
                  .append("x")
                  .append(height);
          return this;
      }
docs: Reduces an image proportionally in order to fit it into given dimensions.
  
  @param width New width
  @param height New height