feat: support reverse button collapsing order in menu-bar

vaadin-menu-bar-flow-parent/vaadin-menu-bar-flow/src/main/java/com/vaadin/flow/component/menubar/MenuBar.java

@@ -364,6 +364,30 @@ public boolean isOpenOnHover() {
         return getElement().getProperty("openOnHover", false);
     }
 
+    /**
+     * Sets reverse collapse order for the menu bar.
+     *
+     * @param reverseCollapseOrder
+     *            If {@code true}, the buttons will be collapsed into the
+     *            overflow menu starting from the "start" end of the bar instead
+     *            of the "end".
+     */
+    public void setReverseCollapseOrder(boolean reverseCollapseOrder) {
+        getElement().setProperty("reverseCollapse", reverseCollapseOrder);
+    }
+
+    /**
+     * Gets whether the menu bar uses reverse collapse order.
+     *
+     * @return {@code true} if the buttons will be collapsed into the overflow
+     *         menu starting from the "start" end of the bar instead of the
+     *         "end".
+     *
+     */
+    public boolean isReverseCollapseOrder() {
+        return getElement().getProperty("reverseCollapse", false);
+    }
+
     /**
      * Gets the internationalization object previously set for this component.
      * <p>

vaadin-menu-bar-flow-parent/vaadin-menu-bar-flow/src/test/java/com/vaadin/flow/component/menubar/tests/MenuBarTest.java

@@ -93,6 +93,21 @@ public void implementsHasOverlayClassName() {
                         .isAssignableFrom(new MenuBar().getClass()));
     }
 
+    @Test
+    public void isReverseCollapseOrder() {
+        Assert.assertFalse(menuBar.isReverseCollapseOrder());
+        Assert.assertFalse(
+                menuBar.getElement().getProperty("reverseCollapse", false));
+    }
+
+    @Test
+    public void setReverseCollapseOrder_isReverseCollapseOrder() {
+        menuBar.setReverseCollapseOrder(true);
+        Assert.assertTrue(menuBar.isReverseCollapseOrder());
+        Assert.assertTrue(
+                menuBar.getElement().getProperty("reverseCollapse", false));
+    }
+
     private void assertChildrenAndItems(MenuItem... expected) {
         Object[] menuItems = menuBar.getChildren().toArray();
         Assert.assertArrayEquals(expected, menuItems);