No so sure, but as you are running in a VPS Linux box (and probably
without X) you may need to run  in headless mode enabled.

From JDK 1.4, Java2D has built in support for headless graphics and
automatically switches to those implementations, when enabled via
'-Djava.awt.headless=true'.

Also don't forget to have headless mode graphics libraries installed (and
pointed by LD_LIBRARY_PATH).
See:
javatechniques.com/.../...ess-java-x11-libraries.h\
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