[FIXED JENKINS-20415] Lack of type safety in JENKINS-20143 fix sometimes caused CCEs.

changelog.html

@@ -69,6 +69,9 @@ Upcoming changes</a>
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-20191">issue 20191</a>)
   <li class=rfe>
     Collect and report JVM crash dump files to assist trouble-shooting
+  <li class=bug>
+      <code>ClassCastException</code>s sometimes shown from views set to be recursive.
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-20415">issue 20415</a>)
   <li class=rfe>
     Show different “up” link for jobs in folders.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-20106">issue 20106</a>)

core/src/main/java/hudson/model/ListView.java

@@ -186,14 +186,12 @@ public class ListView extends View implements Saveable {
     }
 
     private List<TopLevelItem> expand(Collection<TopLevelItem> items, List<TopLevelItem> allItems) {
-        for (Item item : items) {
+        for (TopLevelItem item : items) {
             if (item instanceof ItemGroup) {
-                ItemGroup<TopLevelItem> ig = (ItemGroup<TopLevelItem>) item;
-                expand(ig.getItems(), allItems);
-            }
-            if (item instanceof TopLevelItem) {
-                allItems.add((TopLevelItem) item);
+                ItemGroup<? extends Item> ig = (ItemGroup<? extends Item>) item;
+                expand(Util.filter(ig.getItems(), TopLevelItem.class), allItems);
             }
+            allItems.add(item);
         }
         return allItems;
     }

test/src/test/java/hudson/model/ListViewTest.java

@@ -40,6 +40,10 @@ import org.xml.sax.SAXException;
 
 import com.gargoylesoftware.htmlunit.html.HtmlAnchor;
 import com.gargoylesoftware.htmlunit.html.HtmlPage;
+import hudson.matrix.AxisList;
+import hudson.matrix.MatrixProject;
+import hudson.matrix.TextAxis;
+import java.util.Collections;
 
 public class ListViewTest {
 
@@ -95,4 +99,17 @@ public class ListViewTest {
       webClient.getPage(top, link.getHrefAttribute());
     }
 
+    @Bug(20415)
+    @Test public void nonTopLevelItemGroup() throws Exception {
+        MatrixProject mp = j.createMatrixProject();
+        mp.setAxes(new AxisList(new TextAxis("axis", "one", "two")));
+        assertEquals(2, mp.getItems().size());
+        ListView v = new ListView("v");
+        j.jenkins.addView(v);
+        v.setIncludeRegex(".*");
+        v.setRecurse(true);
+        // Note: did not manage to reproduce CCE until I changed expand to use ‘for (TopLevelItem item : items)’ rather than ‘for (Item item : items)’; perhaps a compiler-specific issue?
+        assertEquals(Collections.singletonList(mp), v.getItems());
+    }
+
 }