code: protected String colorString(PDColor pdcolor)
      {
          String color = null;
          try
          {
              float[] rgb = pdcolor.getColorSpace().toRGB(pdcolor.getComponents());
              color = colorString(rgb[0], rgb[1], rgb[2]);
          } catch (IOException e) {
              log.error("colorString: IOException: {}", e.getMessage());
          } catch (UnsupportedOperationException e) {
              log.error("colorString: UnsupportedOperationException: {}", e.getMessage());
          }
          return color;
      }
docs: Creates a CSS rgb specification from a PDF color
  @param pdcolor
  @return the rgb() string