FULL PRODUCT VERSION :
java version "1.6.0_19"
Java(TM) SE Runtime Environment (build 1.6.0_19-b04)
Java HotSpot(TM) Client VM (build 16.2-b04, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP Service Pack 3

A DESCRIPTION OF THE PROBLEM :
Querying the resource URL of a directory, e. g. Example.class.getResource("/example/"), triggers the mixed code warning introduced in JRE 1.6.0_19 even if all classes and resources in the Jar are signed.

We use this to get a list of all files in the directory as in
((JarURLConnection) getResource("/example/").openConnection()).getJarFile() and then iterating over the entries of the Jar file.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Create a Jar file which contains a directory ("example") and a class which does a getResource for the directory (Example.class.getResource("/example/")).
2. Sign the Jar file with jarsigner
3. Write a JNLP file which launches the Jar
4. Launch with Java Web Start


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
No mixed code warning shown, getResource returns a JarURLConnection
ACTUAL -
Mixed code warning, if user clicks "Yes", getResource returns null.

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
Instead of getResource("/directory/"), access a file which you know exists in the directory, e. g. getResource("/directory/KNOWN_FILE")