feat: add conversion to JsonNode AND feat: add JsonSerializer

src/main/java/com/flowingcode/vaadin/jsonmigration/JsonMigration.java

@@ -19,6 +19,7 @@
  */
 package com.flowingcode.vaadin.jsonmigration;
 
+import com.vaadin.flow.component.ClientCallable;
 import com.vaadin.flow.component.page.PendingJavaScriptResult;
 import com.vaadin.flow.dom.DomEvent;
 import com.vaadin.flow.dom.Element;
@@ -63,6 +64,18 @@ private static Class<?> lookup_BaseJsonNode() {
     }
   } 
 
+  /**
+   * Converts a given Java object into the return type of a {@link ClientCallable method}.
+   *
+   * In Vaadin 25, this method converts {@code JsonValue} into {@code JsonNode}.
+   *
+   * @param object the object to convert
+   * @return an {@code Object} suitable to use as the result of a {@code ClientCallable} method.
+   */
+  public static Object convertToClientCallableResult(Object object) {
+    return helper.convertToClientCallableResult(object);
+  }
+
   /**
    * Converts a given Java object into a {@code JsonValue}.
    *

src/main/java/com/flowingcode/vaadin/jsonmigration/JsonMigrationHelper.java

@@ -29,6 +29,8 @@ interface JsonMigrationHelper {
 
   JsonValue convertToJsonValue(Object object);
 
+  Object convertToClientCallableResult(Object object);
+
   Object invoke(Method method, Object instance, Object... args);
 
   ElementalPendingJavaScriptResult convertPendingJavaScriptResult(PendingJavaScriptResult result);

src/main/java/com/flowingcode/vaadin/jsonmigration/JsonMigrationHelper25.java

@@ -55,6 +55,15 @@ public JsonValue convertToJsonValue(Object object) {
     }
   } 
 
+  @Override
+  public Object convertToClientCallableResult(Object object) {
+    if (object instanceof JsonValue) {
+      return convertToJsonNode((JsonValue) object);
+    } else {
+      return object;
+    }
+  }
+
   @Override
   @SneakyThrows
   public Object invoke(Method method, Object instance, Object... args) {