fix: register VaadinServiceInitListener to bundle grid styles

Close #171

Author: javier-godoy

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

@@ -0,0 +1,46 @@
+/*-
+ * #%L
+ * Grid Helpers Add-on
+ * %%
+ * Copyright (C) 2022 - 2026 Flowing Code
+ * %%
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * #L%
+ */
+
+package com.flowingcode.vaadin.addons.gridhelpers;
+
+import com.vaadin.flow.component.dependency.CssImport;
+import com.vaadin.flow.server.ServiceInitEvent;
+import com.vaadin.flow.server.VaadinServiceInitListener;
+
+/**
+ * Ensures that the addon's grid styles are always included in the production bundle.
+ *
+ * <p>{@code VaadinServiceInitListener} subtypes are discovered via ClassGraph reflection and are
+ * always treated as entry points, regardless of how consumers use the addon. Placing the
+ * {@code @CssImport} annotation here guarantees that the grid styles are included even when
+ * {@link GridHelper} is not reachable through bytecode analysis.
+ *
+ * @see <a href="https://github.com/FlowingCode/GridHelpers/issues/171">Issue #171</a>
+ */
+@CssImport(value = GridHelper.GRID_STYLES, themeFor = "vaadin-grid")
+public class GridHelperServiceInitListener implements VaadinServiceInitListener {
+
+  @Override
+  public void serviceInit(ServiceInitEvent event) {
+    // No initialization needed; this class exists solely to anchor the
+    // @CssImport annotation so it is always picked up during the production
+    // bundle build via ClassGraph entry-point seeding.
+  }
+}

src/main/resources/META-INF/services/com.vaadin.flow.server.VaadinServiceInitListener

@@ -0,0 +1 @@
+com.flowingcode.vaadin.addons.gridhelpers.GridHelperServiceInitListener