Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

src/main/java/com/flowingcode/vaadin/jsonmigration/JsonMigrationHelper25.java (1)

171-182: Restore null‑argument validation in typed then(...) override.

The override of then(Class<T> targetType, SerializableConsumer<T> resultHandler, ...) still omits the non‑null precondition checks that the default method provides. As a result:

• resultHandler == null with a JsonValue target will now cause an asynchronous NullPointerException inside the lambda.
• targetType == null is only validated (if at all) by the delegate, and the behavior depends on its implementation.

To keep the contract consistent and fail fast, please validate arguments before branching:

   @Override
   @SuppressWarnings("unchecked")
   public <T> void then(Class<T> targetType, SerializableConsumer<T> resultHandler,
       SerializableConsumer<String> errorHandler) {
+    if (targetType == null) {
+      throw new IllegalArgumentException("Target type cannot be null");
+    }
+    if (resultHandler == null) {
+      throw new IllegalArgumentException("Result handler cannot be null");
+    }
-    if (targetType != null && JsonValue.class.isAssignableFrom(targetType)) {
+    if (JsonValue.class.isAssignableFrom(targetType)) {
       delegate.then(JsonNode.class, wrap(value -> {
         resultHandler.accept(JsonCodec.decodeAs(value, targetType));
       }), errorHandler);
     } else {
       delegate.then(targetType, resultHandler, errorHandler);
     }
   }

This preserves the non‑null contract and avoids deferred NPEs.

src/main/java/com/flowingcode/vaadin/jsonmigration/JsonCodec.java (1)

43-61: Clarify class‑level Javadoc vs current implementation surface.

The class Javadoc advertises a more general “encode to and from JSON” utility (including Element/Component), but the class currently only exposes decodeAs for a smaller set of types. Consider narrowing the Javadoc to match what this helper actually implements, or adding the missing encode/use cases if you intend to support the full contract.

src/main/java/com/flowingcode/vaadin/jsonmigration/JsonMigrationHelper25.java (1)

160-162: Avoid reusing the same generic type name for helper and outer methods.

decodeAs(JsonNode node, Class<T> type) uses T as its type parameter, which is also the type parameter name of the enclosing then/toCompletableFuture methods. This is legal but slightly confusing when reading call sites like decodeAs(node, targetType). Renaming the helper’s parameter to <U> (or similar) would make the type flow clearer.

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro