[macos] Transparency lost on LinearGradient paint when printing to MacOS X printer

A DESCRIPTION OF THE PROBLEM :
I have a LinearGradientPaint with a color that has transparency. This is rendered correctly on screen. When printed to a printer or PDF, the transparency is lost on MacOSX but prints ok in Windows 7 and Windows 10.

REGRESSION : Last worked in version 8u181

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Paint a 2D shape with a LinearGradientPaint. One of the colors should have transparency (alpha value). Use Java print services to print the shape, either to a real printer or PDF. The transparency is not rendered. This may also affect RadialGradientPaint.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Expected that the printed shape would render the same as it appears on screen.
ACTUAL -
Transparency information was lost, shape prints opaque. See also post to StackOverflow:
https://stackoverflow.com/questions/52488056/transparency-lost-on-lineargradient-paint-when-printing-to-macos-x-printer-using


---------- BEGIN SOURCE ----------
import java.awt.*;
import java.awt.print.*;
import javax.swing.*;

public class TestGradient {

    public static class TwoRectangles extends JComponent {

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D)g;
        g2d.setColor(Color.RED);
        g2d.fillRect(0, 75, 500, 150); //paint a red opaque rectangle

        LinearGradientPaint p = new LinearGradientPaint(50, 100, 500, 100, new float[]{0.0f, 1.0f}, new Color[]{Color.GREEN, new Color(128, 128, 128, 128)}, MultipleGradientPaint.CycleMethod.NO_CYCLE);
        g2d.setPaint(p);
        g2d.fillRect(50, 50, 500, 200); //paint a green gradient with transparency
    }
}

public static final TwoRectangles rect = new TwoRectangles();

public static void main(String[] args) throws PrinterException {

    JFrame f = new JFrame("Test Gradient");
    f.setLayout(new BorderLayout());
    f.add(rect);
    f.setSize(600, 300);
    f.setVisible(true);


    PrinterJob printJob = PrinterJob.getPrinterJob();


    Printable prt = new Printable() {

        @Override
        public int print(Graphics graphics, PageFormat pageFormat, int pageIndex) throws PrinterException {
            if (pageIndex > 0)
                return(NO_SUCH_PAGE);

            rect.print(graphics);
            return PAGE_EXISTS;
        }

    };

    printJob.setPrintable(prt);
    if (printJob.printDialog())
          printJob.print();

  }
 }

---------- END SOURCE ----------

FREQUENCY : always