For all Java subsystem debugging, installing the symbols package java-1.6.0-openjdk-debuginfo is essential. All debuginfo sub-packages reside in own repository which needs to be enabled for installation at least. An example yum command:
# yum install --enablerepo=fedora-debuginfo -y java-1.6.0-openjdk-debuginfo
Firefox detected plugin list can be seen by typing the url:
about:plugins
Firefox can be run in debug mode as follows:
$ ICEDTEAPLUGIN_DEBUG=true firefox <URL above> 2>&1 | tee console.log
This will write the standard output also to a file.
Browser plugin also writes files under user's
~/.icedteaplugin/java.stdout ~/.icedteaplugin/java.stderr
All these files are valuable information which can/should be attached to a bug reports.
OpenJDK does not ship the Java console anymore, but one can be found from Firefox Web Developer add-on which is installed separately to the Firefox. Add-ons are installed using Firefox's own software component management system, not Fedora's RPM.