Add sidebar to plugin manager, increase search bar size (#6783)

Co-authored-by: Daniel Beck <1831569+daniel-beck@users.noreply.github.com>
Co-authored-by: Tim Jacomb <21194782+timja@users.noreply.github.com>
Co-authored-by: Basil Crow <me@basilcrow.com>
Co-authored-by: Alexander Brandes <mc.cache@web.de>

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

@@ -154,6 +154,7 @@ import org.kohsuke.stapler.HttpRedirect;
 import org.kohsuke.stapler.HttpResponse;
 import org.kohsuke.stapler.HttpResponses;
 import org.kohsuke.stapler.QueryParameter;
+import org.kohsuke.stapler.StaplerFallback;
 import org.kohsuke.stapler.StaplerOverridable;
 import org.kohsuke.stapler.StaplerProxy;
 import org.kohsuke.stapler.StaplerRequest;
@@ -1386,6 +1387,27 @@ public abstract class PluginManager extends AbstractModelObject implements OnMas
         return !("adopt-this-plugin".equals(label) || "deprecated".equals(label));
     }
 
+    /**
+     * This allows "Update Center" to live at the URL
+     * {@code /pluginManager/updates/} in addition to its {@code /updateCenter/}
+     * URL which is provided by {@link jenkins.model.Jenkins#getUpdateCenter()}.
+     * For purposes of Stapler, this object is the current item serving the
+     * view, and since this is not a {@link hudson.model.ModelObject}, it does
+     * not appear as an additional breadcrumb and only the "Plugin Manager"
+     * breadcrumb is shown.
+     */
+    @Restricted(NoExternalUse.class)
+    public static class UpdateCenterProxy implements StaplerFallback {
+        @Override
+        public Object getStaplerFallback() {
+            return Jenkins.get().getUpdateCenter();
+        }
+    }
+
+    public UpdateCenterProxy getUpdates() {
+        return new UpdateCenterProxy();
+    }
+
     @Restricted(NoExternalUse.class)
     public HttpResponse doPluginsSearch(@QueryParameter String query, @QueryParameter Integer limit) {
         List<JSONObject> plugins = new ArrayList<>();
@@ -1593,7 +1615,7 @@ public abstract class PluginManager extends AbstractModelObject implements OnMas
         boolean dynamicLoad = req.getParameter("dynamicLoad") != null;
         install(plugins, dynamicLoad);
 
-        rsp.sendRedirect("../updateCenter/");
+        rsp.sendRedirect("updates/");
     }
 
     /**
@@ -1898,7 +1920,7 @@ public abstract class PluginManager extends AbstractModelObject implements OnMas
                     element("url", t.toURI().toString()).
                     element("dependencies", dependencies);
             new UpdateSite(UpdateCenter.ID_UPLOAD, null).new Plugin(UpdateCenter.ID_UPLOAD, cfg).deploy(true);
-            return new HttpRedirect("../updateCenter");
+            return new HttpRedirect("updates/");
         } catch (FileUploadException e) {
             throw new ServletException(e);
         }
@@ -2124,7 +2146,7 @@ public abstract class PluginManager extends AbstractModelObject implements OnMas
     @RequirePOST
     public HttpResponse doInstallNecessaryPlugins(StaplerRequest req) throws IOException {
         prevalidateConfig(req.getInputStream());
-        return HttpResponses.redirectViaContextPath("updateCenter");
+        return HttpResponses.redirectViaContextPath("updates/");
     }
 
     /**