fix: fix equality check in NavigationAccessControl (#21083) (#21092)

Fixes #21082

Co-authored-by: Marco Collovati <[email protected]>

Author: vaadin-bot

flow-server/src/main/java/com/vaadin/flow/server/auth/NavigationAccessControl.java

@@ -216,7 +216,7 @@ protected Class<? extends Component> getLoginView() {
      *            the frontend view to use as login view
      */
     public void setLoginView(String loginUrl) {
-        if (loginUrl == this.loginUrl) {
+        if (Objects.equals(loginUrl, this.loginUrl)) {
             // Probably hot reload
             return;
         }

flow-server/src/test/java/com/vaadin/flow/server/auth/NavigationAccessControlTest.java

@@ -279,6 +279,14 @@ public void setLoginViewClassCannotBeCalledAfterSettingString() {
         accessControl.setLoginView(TestLoginView.class);
     }
 
+    @Test
+    public void setLoginViewStringShouldNotThrowWithSameString() {
+        accessControl.setLoginView("/foo");
+        accessControl.setLoginView("/foo");
+        accessControl.setLoginView(new String("/foo"));
+        Assert.assertEquals("/foo", accessControl.getLoginUrl());
+    }
+
     @Test
     public void beforeEnter_loginView_accessToLoginViewAlwaysAllowed() {
         mockCheckerResult(checker1, AccessCheckDecision.DENY);