Address a number of code review comments and add a test for missing C…

…ds aggregate and eds entries.

xds/src/main/java/io/grpc/xds/XdsRouteConfigureResource.java

@@ -136,7 +136,7 @@ protected RdsUpdate doParse(XdsResourceType.Args args, Message unpackedMessage)
         (RouteConfiguration) unpackedMessage, FilterRegistry.getDefaultRegistry(), args);
   }
 
-  static RdsUpdate processRouteConfiguration(
+  private static RdsUpdate processRouteConfiguration(
       RouteConfiguration routeConfig, FilterRegistry filterRegistry, XdsResourceType.Args args)
       throws ResourceInvalidException {
     return new RdsUpdate(extractVirtualHosts(routeConfig, filterRegistry, args));