[FIX JENKINS-43848] - Lack of cache-invalidation headers results in stale item list (#2973)

* Saving progress for review

* Adding licenses

* Adding integration test for headers

* Removing proposal for refactoring to method objects

* Removing whitespace changeswq

* Fixing test

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

@@ -1053,6 +1053,10 @@ public abstract class View extends AbstractModelObject implements AccessControll
      */
     @Restricted(DoNotUse.class)
     public Categories doItemCategories(StaplerRequest req, StaplerResponse rsp, @QueryParameter String iconStyle) throws IOException, ServletException {
+
+        rsp.addHeader("Cache-Control", "no-cache, no-store, must-revalidate");
+        rsp.addHeader("Pragma", "no-cache");
+        rsp.addHeader("Expires", "0");
         getOwner().checkPermission(Item.CREATE);
         Categories categories = new Categories();
         int order = 0;

test/src/test/java/hudson/model/ViewTest.java

@@ -25,6 +25,7 @@ package hudson.model;
 
 import com.gargoylesoftware.htmlunit.WebRequest;
 import com.gargoylesoftware.htmlunit.html.DomNodeUtil;
+import com.gargoylesoftware.htmlunit.util.NameValuePair;
 import jenkins.model.Jenkins;
 import org.jvnet.hudson.test.Issue;
 import com.gargoylesoftware.htmlunit.FailingHttpStatusCodeException;
@@ -53,11 +54,15 @@ import hudson.util.HudsonIsLoading;
 import java.io.File;
 import java.io.IOException;
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.logging.Level;
 import java.util.logging.LogRecord;
 import jenkins.model.ProjectNamingStrategy;
 import jenkins.security.NotReallyRoleSensitiveCallable;
+
+import static org.hamcrest.CoreMatchers.is;
 import static org.junit.Assert.*;
 import org.junit.Ignore;
 import org.junit.Rule;
@@ -85,6 +90,26 @@ public class ViewTest {
         assertNotNull(j.createWebClient().goTo("").getWebResponse().getResponseHeaderValue("X-Hudson"));
     }
 
+    @Issue("JENKINS-43848")
+    @Test public void testNoCacheHeadersAreSet() throws Exception {
+        List<NameValuePair> responseHeaders = j.createWebClient()
+                .goTo("view/all/itemCategories", "application/json")
+                .getWebResponse()
+                .getResponseHeaders();
+
+
+        final Map<String, String> values = new HashMap<>();
+
+        for(NameValuePair p : responseHeaders) {
+            values.put(p.getName(), p.getValue());
+        }
+
+        String resp = values.get("Cache-Control");
+        assertThat(resp, is("no-cache, no-store, must-revalidate"));
+        assertThat(values.get("Expires"), is("0"));
+        assertThat(values.get("Pragma"), is("no-cache"));
+    }
+
     /**
      * Creating two views with the same name.
      */