Issue #5022 Filter Cache cleanup

Issue #5022 Filter Cache cleanup:
 + Fixed many compiler warnings
 + removed old LazyList leftovers
 + Don't create holder string for source unless required
 + Only have a single type of chain, so it can be wrapped regardless of cache
 + Reverse mappings lists to make filter chain creation easier
 + build chain directly rather than build a list then a chain

Signed-off-by: Greg Wilkins <gregw@webtide.com>

jetty-server/src/main/java/org/eclipse/jetty/server/Request.java

@@ -195,7 +195,7 @@ public static Request getBaseRequest(ServletRequest request)
     private String _servletPath;
     private String _pathInfo;
     private boolean _secure;
-    private String _asyncNotSupportedSource = null;
+    private Object _asyncNotSupportedSource = null;
     private boolean _newContext;
     private boolean _cookiesExtracted = false;
     private boolean _handled = false;
@@ -1940,7 +1940,7 @@ public void removeEventListener(final EventListener listener)
         _requestAttributeListeners.remove(listener);
     }
 
-    public void setAsyncSupported(boolean supported, String source)
+    public void setAsyncSupported(boolean supported, Object source)
     {
         _asyncNotSupportedSource = supported ? null : (source == null ? "unknown" : source);
     }