JDK's logical fonts are statically specified in fontconfig.properties files.
This works well on stable platforms (Solaris and Windows).
On Linux variants there is no assurance of the presence of particular fonts
to support particular locales (CJK for example).
For many "supported" variants we have provided carefully tuned fontconfig.properties
files, but on other variants we may default to just the basic support provided
by the JDK's fonts.
It should be possible to greatly improve matters on such platforms by using
libfontconfig to identify suitable fonts. The details of whether this information
is installed ito the JRE, or a per-user location, or always generated at run time