Proposal: X11 icon window color handing patch

[Ichiroh Takiguchi]

Hello,
IBM would like to contribute X11 icon window color handing patch to 
OpenJDK project.

Issue:
It seems some of colors on icon for pseudo color are not appropriate.
Test program is as follows:
======
$ cat IconifiedFrame.java
import java.awt.*;
import java.awt.event.*;

public class IconifiedFrame extends Frame {
  IconifiedFrame() {
    super("IconifiedFrame");
    setSize(100, 100);
    addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent event) { System.exit(0); }
    });
    setExtendedState(Frame.ICONIFIED);
    setVisible(true);
  }
  public static void main(String[] args) {
    new IconifiedFrame();
  }
}
======

To recreate this issue on RHEL7, please try following steps.
(xorg-x11-server-Xephyr and openmotif rpm packages are required)

1. Type following commands from terminal
$ Xephyr :1 -ac -screen 800x600x8 &
$ xterm -display :1 &
2. On xterm on Xephyr
$ mwm &
$ javac IconifiedFrame.java
$ java IconifiedFrame

Reason:
Pseudo color is handled by unsigned byte data.
But Java's byte is signed, it was not converted to unsigned.
Modified code is as follows:
======
--- old/src/java.desktop/unix/classes/sun/awt/X11/XIconWindow.java       
 2018-06-13 16:23:17.889946251 +0900
+++ new/src/java.desktop/unix/classes/sun/awt/X11/XIconWindow.java       
 2018-06-13 16:23:17.274958922 +0900
@@ -281,8 +281,9 @@
                 ColorData cdata = adata.get_color_data(0);
                 int num_colors = cdata.get_awt_numICMcolors();
                 for (int i = 0; i < buf.length; i++) {
-                    buf[i] = (buf[i] >= num_colors) ?
-                        0 : cdata.get_awt_icmLUT2Colors(buf[i]);
+                    int b = Byte.toUnsignedInt(buf[i]);
+                    buf[i] = (b >= num_colors) ?
+                        0 : cdata.get_awt_icmLUT2Colors(b);
                 }
                 bytes = Native.toData(buf);
             } else if (srcBuf instanceof DataBufferInt) {
======

I'd like contribute following 1 file:
M src/java.desktop/unix/classes/sun/awt/X11/XIconWindow.java

I appreciate any feedback please, and how I would go about obtaining a 
sponsor and contributor?

Thanks,
Ichiroh Takiguchi
IBM Japan, Ltd.