If the delegate attribute in the classloader element of the sun-web.xml file is set to its default value of true, classes and resources residing in container-wide library JAR files are loaded in preference to classes and resources packaged within the WAR file, contrary to what is recommended in the Servlet 2.3 specification, section 9.7.2. If set to false, the classloader delegation behavior complies with what is recommended in the Servlet 2.3 specification, section 9.7.2.
Do not package portable programs that use the delegate attribute with the value of true with any classes or interfaces that are a part of the J2EE specification. The behavior of a program that includes such classes or interfaces in its WAR file is undefined. For more information about the classloader element, the Sun Java System Application Server Platform Edition 8.2 Developer’s Guide.