Support dynamically-loaded plugins in CustomClassFilter.Contributed.

core/src/main/java/hudson/PluginManager.java

@@ -150,6 +150,7 @@ import static java.util.logging.Level.FINE;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.SEVERE;
 import static java.util.logging.Level.WARNING;
+import jenkins.security.CustomClassFilter;
 import org.kohsuke.accmod.Restricted;
 import org.kohsuke.accmod.restrictions.NoExternalUse;
 
@@ -858,6 +859,9 @@ public abstract class PluginManager extends AbstractModelObject implements OnMas
                 ((UberClassLoader) uberClassLoader).loaded.clear();
             }
 
+            // TODO antimodular; perhaps should have a PluginListener to complement ExtensionListListener?
+            CustomClassFilter.Contributed.load();
+
             try {
                 p.resolvePluginDependencies();
                 strategy.load(p);