fix: Hide example feature again

flow-server/src/main/java/com/vaadin/experimental/Feature.java

@@ -16,6 +16,7 @@
 package com.vaadin.experimental;
 
 import java.io.Serializable;
+import java.util.Objects;
 
 import com.vaadin.flow.internal.UsageStatistics;
 
@@ -44,8 +45,8 @@ public class Feature implements Serializable {
      */
     public Feature(String title, String id, String moreInfoLink,
             boolean requiresServerRestart) {
-        this.title = title;
-        this.id = id;
+        this.title = Objects.requireNonNull(title);
+        this.id = Objects.requireNonNull(id);
         this.moreInfoLink = moreInfoLink;
         this.requiresServerRestart = requiresServerRestart;
     }
@@ -90,4 +91,25 @@ public void setEnabled(boolean enabled) {
 
         this.enabled = enabled;
     }
+
+    @Override
+    public int hashCode() {
+        return id.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        Feature other = (Feature) obj;
+        return (id.equals(other.id));
+    }
+
 }

flow-test-util/src/main/java/com/vaadin/flow/testutil/DevModeGizmoElement.java

@@ -99,4 +99,13 @@ private void showTab(String id) {
         $("button").attributeContains("class", "tab").id(id).click();
     }
 
+    public void showExperimentalFeatures() {
+        showTab("features");
+    }
+
+    public List<String> listExperimentalFeatures() {
+        return (List<String>) executeScript(
+                "return Array.from(arguments[0].shadowRoot.querySelectorAll('.features-tray .feature label')).map(e => e.textContent.trim())",
+                this);
+    }
 }

flow-tests/test-dev-mode/src/test/java/com/vaadin/flow/uitest/ui/DebugWindowFeatureFlagsIT.java

@@ -0,0 +1,31 @@
+package com.vaadin.flow.uitest.ui;
+
+import java.util.List;
+
+import com.vaadin.flow.component.Component;
+import com.vaadin.flow.testutil.ChromeBrowserTest;
+import com.vaadin.flow.testutil.DevModeGizmoElement;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class DebugWindowFeatureFlagsIT extends ChromeBrowserTest {
+    @Override
+    protected Class<? extends Component> getViewClass() {
+        return DebugWindowErrorHandlingView.class;
+    }
+
+    @Test
+    public void exampleFeatureFlagNotShown() {
+        open();
+        DevModeGizmoElement debugWindow = $(DevModeGizmoElement.class).first();
+        debugWindow.expand();
+        debugWindow.showExperimentalFeatures();
+        List<String> features = debugWindow.listExperimentalFeatures();
+        for (String feature : features) {
+            Assert.assertFalse(
+                    "Example feature should not be shown in the debug window",
+                    feature.contains("Example feature"));
+        }
+    }
+}

vaadin-dev-server/src/main/java/com/vaadin/base/devserver/DebugWindowConnection.java

@@ -118,11 +118,10 @@ public void onConnect(AtmosphereResource resource) {
                 resource);
 
         send(resource, "serverInfo", new ServerInfo());
-        send(resource, "featureFlags",
-                new FeatureFlagMessage(FeatureFlags.get(context).getFeatures()
-                        .stream()
-                        .filter(feature -> feature != FeatureFlags.EXAMPLE)
-                        .collect(Collectors.toList())));
+        send(resource, "featureFlags", new FeatureFlagMessage(FeatureFlags
+                .get(context).getFeatures().stream()
+                .filter(feature -> !feature.equals(FeatureFlags.EXAMPLE))
+                .collect(Collectors.toList())));
     }
 
     private void send(AtmosphereResource resource, String command,