We are currently porting their applications/framework from JBoss AS 6 to our supported JBoss EAP 5.1. During this exercise we found a bug in the org.apache.el.lang.ELSupport class. When passing a 'null' reference and 'Number' type to the 'coerceToType' method an 'java.lang.IllegalArgumentException: Cannot convert 0 of type class java.lang.Long to class java.lang.Number' is thrown. The bug is actually in the 'coerceToNumber(final Number number, final Class type)' method, which should check whether the 'type' is the Number class, and if it is, just return the 'number'.

This issue has been fixed in the ELSupport class of Apache Tomcat 6.0.21. See also: https://issues.apache.org/bugzilla/show_bug.cgi?id=43656 (comment 26 to 29). I had a look at JBossWeb 2.1.11.GA, which is the new JBossWeb that will be included in EAP 5.1.1, but that version of JBossWeb still contains this bug.

I've attached the stack trace, the ELSupport class of Tomcat 6.0.20 and the ELSupport class of Tomcat 6.0.21 (which includes the fix). The fix is at line numbers 249,250 and 251 in the 6.0.21 version of the class.