Was all my fault.
Thanks to Dirks question reg. the startup process I double-checked the bash launcher script which my colleague wrote and saw that he starts java with /Library/Java/Home/bin/java -jar ...
instead of using only java -jar ...
.
While java
points to the Java 6 JDK, /Library/Java/Home/bin/java
still points to old Java 5. Bummer! :-(
With using java -jar ...
instead in the bash script, everything works fine now...