The issue appears when 32-bit jdk bundles are used on 64-bit machine.
When you try to set Nimbus LAF, you get NPE, and when you try to set GTK LAF, you get UnsupportedLookAndFeelException, though this LAF was in the list obtained by UIManager.getInstalledLookAndFeels()

Part of the log:

Look and Feel to be set:
 javax.swing.plaf.nimbus.NimbusLookAndFeel
java.lang.NullPointerException
at sun.font.FontConfigManager.getFontConfigFont(FontConfigManager.java:352)
at sun.awt.X11FontManager.getFontConfigFUIR(X11FontManager.java:817)
at sun.font.FontUtilities.getFontConfigFUIR(FontUtilities.java:488)
at javax.swing.plaf.nimbus.NimbusDefaults.<init>(NimbusDefaults.java:138)
at javax.swing.plaf.nimbus.NimbusLookAndFeel.<init>(NimbusLookAndFeel.java:100)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
at java.lang.Class.newInstance0(Class.java:372)
at java.lang.Class.newInstance(Class.java:325)
at javax.swing.UIManager.setLookAndFeel(UIManager.java:579)
at bug4492274.doTest(bug4492274.java:143)
at bug4492274.runTest(bug4492274.java:93)
at bug4492274.main(bug4492274.java:53)

----------------------
Look and Feel to be set:
 com.sun.java.swing.plaf.gtk.GTKLookAndFeel
javax.swing.UnsupportedLookAndFeelException: [GTK look and feel - com.sun.java.swing.plaf.gtk.GTKLookAndFeel] not supported on this platform
at javax.swing.UIManager.setLookAndFeel(UIManager.java:522)
at javax.swing.UIManager.setLookAndFeel(UIManager.java:579)
at bug4492274.doTest(bug4492274.java:143)
at bug4492274.runTest(bug4492274.java:93)
at bug4492274.main(bug4492274.java:53)