Possible null pointer in FormAuthenticator

Originally reported as Bug 305799 by Slawek Rudnicki <slawek.rudnicki@gmail.com>:

In version 6.1.22 of the Jetty server, in
org.mortbay.jetty.security.FormAuthenticator, line 179 we have this snippet of
code:

if (response != null)
response.setContentLength(0);
response.sendRedirect(response.encodeRedirectURL
(URIUtil.addPaths(request.getContextPath(), formErrorPage)));

which seems to lack brackets around the instructions, leading to a possible
NullPointerException thrown when response happens to be null.

The indentation there made the bug difficult to spot by a programmer. In fact,
I have found the bug using FindBugs as part of a course on static analysis on
my university. There are some other problems indicated by FindBugs, which I –
being unfamiliar with Jetty code – cannot determine to be spurious or not.
Maybe you can use the tool to find and fix some similar issues.

Hope that helps