Manifest should not include classpath. It is not compatible with many of deployment optimization/hints.
WebStart is ignoring classpath attribute but plugin2 can not do this due to backward compatibility (need to be able to run old applets) and JNLP applets suffer from classpath entry a lot.
Fixed in jet-main: dfe201a2af9e
Integrated into 'main-golden', will be available in build *201002270200* on http://bits.netbeans.org/dev/nightly/ (upload may still be in progress)
User: Tomas Zezula <firstname.lastname@example.org>
Log: #181260:Do not add Class-Path attribute into applet jar