Applicable to JBoss 4.0.4 GA:
Suppose you are using jdk 1.5 features in JSPs but they fail with following exception
jboss jsp Syntax error, parameterized types are only available if source level is 5.0
that means you need to enable jdk 1.5 vm support for JSPs.
For this, open /opt/jboss/server//deploy/jbossweb-tomcat55.sar/conf/web.xml file (replace with default if you have only one instance, otherwise use what is applicable), and search following text:
<!– Uncomment to use jdk1.5 features in jsp pages compilerSourceVM 1.5 –>
As you can clearly see, it is asking to uncomment enclosed tag to enable 1.5 version for jsp pages. Uncomment above block and restart server. You are good to go now.