code: private Color buildGrayColor(final GrayColor gColor) {
          Color color = null;
          if (gColor.opacity() >= 1.0) {
              color = Color.gray(gColor.gray());
          } else {
              color = Color.gray(gColor.gray(), gColor.opacity());
          }
          return color;
      }
docs: Build a Gray color.
  
  @param gColor the gray color enum
  
  @return the javafx color