feat: allow matching navigation hierarchies with side nav item (#6583)

vaadin-side-nav-flow-parent/vaadin-side-nav-flow/src/main/java/com/vaadin/flow/component/sidenav/SideNavItem.java

@@ -394,6 +394,34 @@ public void setTarget(String target) {
         }
     }
 
+    /**
+     * Gets whether this item also matches nested paths / routes.
+     *
+     * @return true if this item also matches nested paths / routes, false
+     *         otherwise
+     */
+    public boolean isMatchNested() {
+        return getElement().getProperty("matchNested", false);
+    }
+
+    /**
+     * Sets whether to also match nested paths / routes. {@code false} by
+     * default.
+     * <p>
+     * When enabled, an item with the path {@code /path} is considered current
+     * when the browser URL is {@code /path}, {@code /path/child},
+     * {@code /path/child/grandchild}, etc.
+     * <p>
+     * Note that this only affects matching of the URLs path, not the base
+     * origin or query parameters.
+     *
+     * @param value
+     *            true to also match nested paths / routes, false otherwise
+     */
+    public void setMatchNested(boolean value) {
+        getElement().setProperty("matchNested", value);
+    }
+
     /**
      * @return true if this item should be ignored by the Vaadin router and
      *         behave like a regular anchor.

vaadin-side-nav-flow-parent/vaadin-side-nav-flow/src/test/java/com/vaadin/flow/component/sidenav/tests/SideNavItemTest.java

@@ -621,6 +621,24 @@ public void targetDefined_setToNull_noTarget() {
         Assert.assertNull(sideNavItem.getTarget());
     }
 
+    @Test
+    public void isMatchNested_falseByDefault() {
+        Assert.assertFalse(sideNavItem.isMatchNested());
+    }
+
+    @Test
+    public void setMatchNested_isMatchNested() {
+        sideNavItem.setMatchNested(true);
+        Assert.assertTrue(
+                sideNavItem.getElement().getProperty("matchNested", false));
+        Assert.assertTrue(sideNavItem.isMatchNested());
+
+        sideNavItem.setMatchNested(false);
+        Assert.assertFalse(
+                sideNavItem.getElement().getProperty("matchNested", false));
+        Assert.assertFalse(sideNavItem.isMatchNested());
+    }
+
     @Test
     public void isRouterIgnore_falseByDefault() {
         Assert.assertFalse(sideNavItem.isRouterIgnore());