fix: ensure dense theme CSS is included in production bundle

Add setDenseTheme(Grid, boolean) and isDenseTheme(Grid) methods that
create a bytecode reference to GridHelper, ensuring the Vaadin production
bundle scanner discovers its @CssImport annotations.

The DENSE_THEME constant is a compile-time constant (static final String),
so javac inlines it at the call site. When a consumer only uses the
constant (e.g. grid.addThemeName(GridHelper.DENSE_THEME)), no bytecode
reference to GridHelper is emitted and the scanner never reaches it.

DENSE_THEME is deprecated in favor of the new methods.

Closes #171

Co-authored-by: Javier Godoy <11554739+javier-godoy@users.noreply.github.com>

Author: Timo Meinen

README.md

@@ -84,7 +84,7 @@ The class `GridHelper` provides several static methods that receive a `Grid` or
 
 ```
 grid.setSelectionMode(SelectionMode.MULTI);
-grid.addThemeName(GridHelper.DENSE_THEME);
+GridHelper.setDenseTheme(grid, true);
 GridHelper.setSelectOnClick(grid, true);
 GridHelper.setArrowSelectionEnabled(grid, true);
 GridHelper.setSelectionColumnHidden(grid, true);

src/main/java/com/flowingcode/vaadin/addons/gridhelpers/GridHelper.java

@@ -78,7 +78,45 @@ public final class GridHelper<T> implements Serializable {
 
   /** Compact row styling for Vaadin Grid */
   // https://cookbook.vaadin.com/grid-dense-theme
-  public static final String DENSE_THEME = "fcGh-dense";
+  private static final String DENSE_THEME_NAME = "fcGh-dense";
+
+  /**
+   * Compact row styling for Vaadin Grid.
+   *
+   * @deprecated Use {@link #setDenseTheme(Grid, boolean)} instead. Direct use of this constant
+   *     bypasses the bytecode reference to {@code GridHelper}, which prevents the Vaadin production
+   *     bundle scanner from discovering the required {@code @CssImport} annotations.
+   */
+  @Deprecated(since = "2.1.0", forRemoval = true)
+  public static final String DENSE_THEME = DENSE_THEME_NAME;
+
+  /**
+   * Adds or removes compact row styling on the given grid.
+   *
+   * <p>Prefer this method over {@code grid.addThemeName(GridHelper.DENSE_THEME)} because it
+   * creates a bytecode reference to {@code GridHelper}, ensuring that the Vaadin production
+   * bundle scanner discovers the required {@code @CssImport} annotations.
+   *
+   * @param grid the grid to style
+   * @param dense {@code true} to enable dense theme, {@code false} to remove it
+   */
+  public static void setDenseTheme(Grid<?> grid, boolean dense) {
+    if (dense) {
+      grid.addThemeName(DENSE_THEME_NAME);
+    } else {
+      grid.removeThemeName(DENSE_THEME_NAME);
+    }
+  }
+
+  /**
+   * Returns whether the dense theme is currently applied to the given grid.
+   *
+   * @param grid the grid to check
+   * @return {@code true} if the dense theme is applied
+   */
+  public static boolean isDenseTheme(Grid<?> grid) {
+    return grid.hasThemeName(DENSE_THEME_NAME);
+  }
 
   @Getter(value = AccessLevel.PACKAGE)
   private final Grid<T> grid;

src/test/java/com/flowingcode/vaadin/addons/gridhelpers/AllFeaturesDemo.java

@@ -263,15 +263,11 @@ private boolean hasSelectionFilter(Grid<Person> grid) {
   }
 
   private void setDenseTheme(Grid<Person> grid, boolean value) {
-    if (value) {
-      grid.addThemeName(GridHelper.DENSE_THEME);
-    } else {
-      grid.removeThemeName(GridHelper.DENSE_THEME);
-    }
+    GridHelper.setDenseTheme(grid, value);
   }
 
   private boolean hasDenseTheme(Grid<Person> grid) {
-    return grid.hasThemeName(GridHelper.DENSE_THEME);
+    return GridHelper.isDenseTheme(grid);
   }
 
   private void setHeaderHidden(Grid<Person> grid, boolean value) {

src/test/java/com/flowingcode/vaadin/addons/gridhelpers/DenseThemeDemo.java

@@ -44,7 +44,7 @@ public DenseThemeDemo() {
     grid.addColumn(Person::getLastName).setHeader("Last name");
     grid.addColumn(Person::getCountry).setHeader("Country");
 
-    grid.addThemeName(GridHelper.DENSE_THEME);
+    GridHelper.setDenseTheme(grid, true);
 
     grid.setHeightFull();
     add(grid);