Fix: Prevent undefined properties at the root level

Fixes: rjsf-team#3424 by preventing the inclusion of undefined properties at the root level
- Updated `@rjsf/utils`, making `computDefaults` helper in `getDefaultFormState()` to skip adding undefined values when `excludeObjectChildren` is set.
  - This basically supports adding an empty object
  - Updated the tests accordingly
- Updated the `CHANGELOG.md` accordingly

CHANGELOG.md

@@ -20,6 +20,9 @@ should change the heading of the (upcoming) version to include a major version b
 ## @rjsf/chakra-ui
 - Fixed the `SelectWidget` to allow the proper display of the selected value, fixing [#3422](https://github.com/rjsf-team/react-jsonschema-form/issues/3422)
 
+## @rjsf/utils
+- Fixed `computeDefaults` to not put undefined values into an object when `excludeObjectChildren` is provided, fixing [#3424](https://github.com/rjsf-team/react-jsonschema-form/issues/3424)
+
 # 5.0.2
 
 ## @rjsf/utils

packages/utils/src/schema/getDefaultFormState.ts

@@ -199,7 +199,10 @@ export function computeDefaults<
               : includeUndefinedValues
           );
           if (includeUndefinedValues) {
+            // When "excludeObjectChildren" don't assign undefined values
+            // if (includeUndefinedValues === true || computedDefault !== undefined) {
             acc[key] = computedDefault;
+            // }
           } else if (isObject(computedDefault)) {
             // Store computedDefault if it's a non-empty object (e.g. not {})
             if (!isEmpty(computedDefault)) {

packages/utils/test/schema/getDefaultFormStateTest.ts

@@ -114,7 +114,10 @@ export default function getDefaultFormStateTest(
         const schema: RJSFSchema = {
           type: "object",
           properties: {
-            optionalProperty: {
+            optionalNumberProperty: {
+              type: "number",
+            },
+            optionalObjectProperty: {
               type: "object",
               properties: {
                 nestedRequiredProperty: {
@@ -145,9 +148,7 @@ export default function getDefaultFormStateTest(
             "excludeObjectChildren"
           )
         ).toEqual({
-          optionalProperty: {
-            nestedRequiredProperty: undefined,
-          },
+          optionalObjectProperty: {},
           requiredProperty: "foo",
         });
       });