Active Flushing: OutOfMemory exception due to TimedCachePolicy in JAAS

We have a big amount of users who perform logon to jboss.
After 15 000 user logins we have an OutOfMemory exception.
During profiling we see that JAASSecurityManager$DomainInfo takes almost all memory.
We are using <attribute name="DefaultCacheTimeout">120</attribute> and <attribute name="DefaultCacheResolution">60</attribute>
But memory is only growing. So no objects are removed from authentication cache.
We tried to disable caching but in that case we had from time to time Authentication failure exception then did logon from multiple clients.
After digging into source code we saw that object never removed from cache !
Only then user do re-logon it is checked that principa is expired and removed.
But it means that If user logged on once it will be always (!!) in cache.
And it leads to OutOfMemory.
We had to extend a run() method of TimedCachePolicy to do remove expired objects:

public void run() {
super.run();
synchronized (entryMap) {
Iterator iter = entryMap.entrySet().iterator();
List<Object> removeentries = new ArrayList<Object>();
while (iter.hasNext()) {
Map.Entry entry = (Map.Entry) iter.next();
TimedEntry value = (TimedEntry) entry.getValue();

if (value.isCurrent(now) == false) {
if(log.isDebugEnabled())

{ log.debug("destroying object:"+value); }

value.destroy();
removeentries.add(entry.getKey());
}

}
for (Object object : removeentries) {
if(log.isDebugEnabled())

{ log.debug("removing object from Map:"+object); }

entryMap.remove(object);
}
}

}

Is not it will be much better to do it on original TimedCachePolicy class ?