Error page lookup does not conform to the servlet spec

[VsevolodGolovanov]

WebXml#findErrorPageLocation is incorrect, because it doesn't satisfy the rule of the servlet spec: The closest match in the class hierarchy wins. WebXml uses the first encountered superclass instead.
Here is how Undertow does it:

String location = null;
for (Class c = exception.getClass(); c != null && location == null; c = c.getSuperclass()) {
    location = exceptionMappings.get(c);
}

https://github.com/undertow-io/undertow/blob/master/servlet/src/main/java/io/undertow/servlet/core/ErrorPages.java

WebXml also doesn't do the unwrap the ServletException and do a second pass step, but I guess this is intentional, because WebXml#findErrorPageLocation is intended to be called inside the Servlet#service execution, before ServletException wrapping could occur.

[BalusC]

Fix is available in today's snapshot. Thank you for reporting!