The getContext() method incorrectly returns null when requesting the ROOT context ("/"). The following fix resolves the issue:

public ServletContext getContext(String uri) {

// Validate the format of the specified argument
if ((uri == null) || (!uri.startsWith("/")))
return (null);

Context child = null;
try {
// Look for an exact match
Container host = context.getParent();
child = (Context) host.findChild(uri);
if ( (child == null) && "/".equals(uri) )

// fix

The root context was created via:

Context context = embedded.addWebapp("", "/path/to/webapps/ROOT");

https://bz.apache.org/bugzilla/show_bug.cgi?id=57645
http://svn.apache.org/r1662178