Breadcrumb is reworked to show descendants to provide additional navigational shortcuts.

Object that implements ModelObjectWithChildren can expose its children in the breadcrumb.

core/src/main/java/hudson/Functions.java

@@ -127,6 +127,7 @@ import jenkins.model.GlobalConfiguration;
 import jenkins.model.GlobalConfigurationCategory;
 import jenkins.model.GlobalConfigurationCategory.Unclassified;
 import jenkins.model.Jenkins;
+import jenkins.model.ModelObjectWithChildren;
 import jenkins.model.ModelObjectWithContextMenu;
 
 import org.acegisecurity.providers.anonymous.AnonymousAuthenticationToken;
@@ -183,6 +184,10 @@ public class Functions {
         return o instanceof ModelObjectWithContextMenu;
     }
 
+    public static boolean isModelWithChildren(Object o) {
+        return o instanceof ModelObjectWithChildren;
+    }
+
     public static String xsDate(Calendar cal) {
         return Util.XS_DATETIME_FORMATTER.format(cal.getTime());
     }