fix work around classloaders for field preencoders

jetty-http/src/main/java/org/eclipse/jetty/http/PreEncodedHttpField.java

@@ -52,7 +52,7 @@ public class PreEncodedHttpField extends HttpField
         {
             try
             {
-                HttpFieldPreEncoder enc = iter.next();
+                encoders.add(iter.next());
             }
             catch(Error|RuntimeException e)
             {

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

@@ -366,6 +366,19 @@ public abstract class AbstractConnector extends ContainerLifeCycle implements Co
                 _defaultProtocol=factory.getProtocol();
         }
     }
+    
+    public void addIfAbsentConnectionFactory(ConnectionFactory factory)
+    {
+        synchronized (_factories)
+        {
+            if (_factories.containsKey(factory.getProtocol()))
+                return;
+            _factories.put(factory.getProtocol().toLowerCase(Locale.ENGLISH), factory);
+            addBean(factory);
+            if (_defaultProtocol==null)
+                _defaultProtocol=factory.getProtocol();
+        }
+    }
 
     public ConnectionFactory removeConnectionFactory(String protocol)
     {