This test reliably fails on my Xubuntu 20.04:

$ CONF=linux-x86_64-server-fastdebug make run-test TEST=java/awt/font/GlyphVector/NLGlyphTest.java

...

STDERR:
java.lang.ArrayIndexOutOfBoundsException: Index 0 out of bounds for length 0
at java.desktop/sun.font.StandardGlyphVector.getGlyphCode(StandardGlyphVector.java:310)
at NLGlyphTest.main(NLGlyphTest.java:46)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
at java.base/java.lang.Thread.run(Thread.java:833)

JavaTest Message: Test threw exception: java.lang.ArrayIndexOutOfBoundsException: Index 0 out of bounds for length 0
JavaTest Message: shutting down test

Seems to fail here:

   public static void main(String[] args) {
      char[] chs = { '\n' };
      FontRenderContext frc = new FontRenderContext(null, true, true);
      GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
      Font[] fonts = ge.getAllFonts();
      for (Font font : fonts) {
          GlyphVector cgv = font.createGlyphVector(frc, "\n");
          GlyphVector lgv = font.layoutGlyphVector(frc, chs, 0, 1, 0);
          int c_code = cgv.getGlyphCode(0);
          int l_code = lgv.getGlyphCode(0); <--- AIIOB

Seems that "\n" produced no glyphs? I assume this is a test bug. [~prr], please advise how to fix this test?