fix: Prefix web component client app with wc- (#15315)

Avoids conflicts with the application

Author: Artur-

flow-server/src/main/java/com/vaadin/flow/component/UI.java

@@ -206,8 +206,29 @@ public int getUIId() {
      *            the id of the new ui
      *
      * @see #getUIId()
+     * @deprecated Use {@link #doInit(VaadinRequest, int, String)} instead
      */
+    @Deprecated
     public void doInit(VaadinRequest request, int uiId) {
+        doInit(request, uiId,
+                getSession().getService().getMainDivId(getSession(), request));
+    }
+
+    /**
+     * Internal initialization method, should not be overridden. This method is
+     * not declared as final because that would break compatibility with e.g.
+     * CDI.
+     *
+     * @param request
+     *            the initialization request
+     * @param uiId
+     *            the id of the new ui
+     * @param appId
+     *            the application id
+     *
+     * @see #getUIId()
+     */
+    public void doInit(VaadinRequest request, int uiId, String appId) {
         if (this.uiId != -1) {
             String message = "This UI instance is already initialized (as UI id "
                     + this.uiId
@@ -224,8 +245,6 @@ public void doInit(VaadinRequest request, int uiId) {
         }
         this.uiId = uiId;
 
-        String appId = getSession().getService().getMainDivId(getSession(),
-                request);
         appId = APP_ID_REPLACE_PATTERN.matcher(appId).replaceAll("");
         getInternals().setAppId(appId);
 

flow-server/src/main/java/com/vaadin/flow/component/webcomponent/WebComponentUI.java

@@ -59,8 +59,8 @@ public class WebComponentUI extends UI {
     public static final String NO_NAVIGATION = "Navigation is not available for WebComponents";
 
     @Override
-    public void doInit(VaadinRequest request, int uiId) {
-        super.doInit(request, uiId);
+    public void doInit(VaadinRequest request, int uiId, String appId) {
+        super.doInit(request, uiId, appId);
 
         assignThemeVariant();
         getEventBus().addListener(WebComponentConnectEvent.class,

flow-server/src/main/java/com/vaadin/flow/server/BootstrapHandler.java

@@ -362,9 +362,6 @@ public PushMode getPushMode() {
         /**
          * Gets the application id.
          *
-         * The application id is defined by
-         * {@link VaadinService#getMainDivId(VaadinSession, VaadinRequest)}
-         *
          * @return the application id
          */
         public String getAppId() {
@@ -1529,7 +1526,7 @@ protected BootstrapContext createAndInitUI(Class<? extends UI> uiClass,
 
         // Set thread local here so it is available in init
         UI.setCurrent(ui);
-        ui.doInit(request, session.getNextUIid());
+        ui.doInit(request, session.getNextUIid(), context.getAppId());
         session.addUI(ui);
 
         // After init and adding UI to session fire init listeners.

flow-server/src/main/java/com/vaadin/flow/server/communication/WebComponentBootstrapHandler.java

@@ -95,6 +95,11 @@ public <T extends Annotation> Optional<T> getPageConfigurationAnnotation(
         protected Optional<PwaRegistry> getPwaRegistry() {
             return Optional.empty();
         }
+
+        @Override
+        public String getAppId() {
+            return "wc-" + super.getAppId();
+        }
     }
 
     private static class WebComponentBootstrapPageBuilder

flow-server/src/test/java/com/vaadin/flow/component/UITest.java

@@ -189,7 +189,7 @@ private static UI createTestUI() {
         MockLogger mockLogger = new MockLogger();
         UI ui = new UI() {
             @Override
-            public void doInit(VaadinRequest request, int uiId) {
+            public void doInit(VaadinRequest request, int uiId, String appId) {
 
             }