With JDK 16 a jpackage installed swing app is failing with

Exception in thread "main" java.lang.NoClassDefFoundError: Could not initialize class sun.font.SunFontManager

This appears to be a regression due to
8249821: Separate libharfbuzz from libfontmanager

so harfbuzz.dll is now a dependent dll of libfontmanager.dll, as
was already the case for freetype.dll

This isn't seen in apps using the java launcher, but jpackage must
not be setting up the path the same way.

I observe that in src/java.desktop/share/classes/sun/font/FontManagerNativeLibrary.java
for windows we have code like this
               if (System.getProperty("os.name").startsWith("Windows")) {
                   System.loadLibrary("freetype");
               }
               System.loadLibrary("fontmanager");

along with comments about windows dll loading not being able to find
freetype without this.

The same is therefore needed for harfbuzz.