I see. The dependency is inherited from the maven-plug-in. That is why the CAS plug-in does not have it on the classpath.

I'm using the "original" Xerces version due to some class loading issues on slaves and containers when the JDK provided version could not be loaded.

Well, even if all plugins have xerces, you should set the property to previous value (ie clear it) after use, right?

Yes, of course, this is definitely a bug in my plug-in. I just wondered why Xerces is not found by other plug-ins since it is by default on my build path. (And it is also a bug in the another plug-in: it should also check the system property for an valid entry before using it like I'm doing it)

I'm not so sure about that. It's a system property so it should be set by the topmost component, right? That's Jenkins or jetty. If anyone needs to use different parser then he should use it directly and not override system settings. If there are any classloading issues on slaves then it should be fixed by Jenkins, no? (e.g. by using xerces system-wide)

You see, I recently stumbled upon a similar thing. We had a servlet container (Tomcat) with several applications. One of them - for some reason - decided to disable caching (ehcache) by setting some system property. But it is a system property! It effectively disabled caching for all applications in the container. And that's why I think it's just bad.

Code changed in jenkins
User: Ulli Hafner
Path:
src/main/java/hudson/plugins/analysis/util/SaxSetup.java
http://jenkins-ci.org/commit/analysis-core-plugin/9c1db98e801ff2b0eb762b859ab7f5d13b6bd6c1
Log:
[ FIXED JENKINS-20070] Clear SAX system property afterwards.

Code changed in jenkins
User: Ulli Hafner
Path:
src/main/java/hudson/plugins/checkstyle/CheckStylePlugin.java
http://jenkins-ci.org/commit/checkstyle-plugin/7c3d7feb48b885c48db99606b5443c45b63822f3
Log:
[ FIXED JENKINS-20070] Clear SAX system property afterwards.

Code changed in jenkins
User: Ulli Hafner
Path:
plugin/src/main/java/hudson/plugins/findbugs/FindBugsPlugin.java
plugin/src/main/java/hudson/plugins/findbugs/parser/FindBugsParser.java
http://jenkins-ci.org/commit/findbugs-plugin/c28a39643bf8aff1178b91c5602ff95c3bcc6d7c
Log:
[ FIXED JENKINS-20070] Clear SAX system property afterwards.

Code changed in jenkins
User: Ulli Hafner
Path:
src/main/java/hudson/plugins/dry/parser/DuplicationParserRegistry.java
http://jenkins-ci.org/commit/dry-plugin/50667efb70835e1d89068bba917a68877ff575e5
Log:
[ FIXED JENKINS-20070] Clear SAX system property afterwards.

Code changed in jenkins
User: Ulli Hafner
Path:
src/main/java/hudson/plugins/analysis/util/SaxSetup.java
http://jenkins-ci.org/commit/analysis-core-plugin/b5457a8ecc62847e87aa28016de97255128c3c35
Log:
JENKINS-20070 Clear SAX system property afterwards.

Code changed in jenkins
User: Ulli Hafner
Path:
plugin/src/test/java/hudson/plugins/findbugs/parser/FindBugsParserTest.java
http://jenkins-ci.org/commit/findbugs-plugin/9dbc7313bfe3f624db6a6bcefdaa093ad618ddca
Log:
JENKINS-20070 Clear SAX system property afterwards.