java renders 2 combining diacriticals poorly

FULL PRODUCT VERSION :

java version "1.7.0_51"
Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601]


A DESCRIPTION OF THE PROBLEM :
I believe this particular character combination should "work out" to be one character, with two combining diacritical marks on it. Instead it renders 1 character with one combining diacritical mark, and then another "dash circle" with the second diacritical mark.

ADDITIONAL REGRESSION INFORMATION:
Why does it ask for this twice?


java version "1.7.0_51"
Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
run attached code


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
should output

size should be one character long, like:8 but instead is:8

ACTUAL -
size should be one character long, like:8 but instead is:14


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.*;
import java.awt.image.BufferedImage;

/**
 */
public class JavaBug {

  public static void main(String[] args) {
    BufferedImage image = new BufferedImage(100, 100, BufferedImage.TYPE_INT_ARGB);
    Graphics2D graphics2D = image.createGraphics();
    StringBuilder text = new StringBuilder();
    text.appendCodePoint(3588);
    text.appendCodePoint(3640); // combining diacritic mark, should combine with previous character (3588) ??
    text.appendCodePoint(3633); // combining diacritic mark, should combine with previous character (3588) ??
    System.out.println("size should be one character long, like:" + graphics2D.getFontMetrics().charWidth(3588) + " but instead is:" + graphics2D.getFontMetrics().stringWidth(text.toString()));
    System.out.println("this should show one character, and no dash circles;" + text.toString());
  }
}

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