Tomcat/Oracle CLOB gotcha?

Just spent two days troubleshooting why CLOB inserts were failing on one Tomcat install. It came down to two arguments in the resource declaration of my database in Tomcat:

accessToUnderlyingConnectionAllowed="true"
factory="org.apache.commons.dbcp.BasicDataSourceFactory"

The observed failure was that CLOB columns were set to NULL, even though the insert appeared to work. In one table, the CLOB column was declared as XMLTYPE NOT NULL, and inserts would fail with an XMLType error at "line 241". The line 241 the error mentioned was not in my code but in Oracle's.

Besides this, it was necessary to make sure commons-dbcp-1.2.2.jar and commons-pool-1.3.jar were in tomcat's common/lib directory, otherwise I got NoClassDefFound errors in catalinia.out.