#243 - Fix RecursivePropertySetterTransformer: modify stdClass items in place

[njoubert-cleverage]

Description

Fixes #243.

When a \stdClass item did not have the property yet, RecursivePropertySetterTransformer replaced it by a copy ((object) array_merge((array) $item, [...])) in the returned collection, so the object of the input was not modified, contrary to the documentation ("object items are modified in place"). When the property already existed, the item was modified in place.

The property is now added to the item itself ($item->{$propertyPath} = $propertyValue). The output content is unchanged, including for a nested path such as parent.id, which was and still is added as a literal parent.id property (the PropertyAccessor cannot create the intermediate object); only the identity changes. Non-\stdClass items still throw.

Documentation: docs/reference/transformers/recursive_property_setter_transformer.md. Tests: testMissingPropertyIsAddedInPlaceToStdClassItems (fails on main: the returned item is not the input one) and testMissingNestedPropertyPathIsAddedAsPropertyToStdClassItems.

PHPUnit (803 tests), PHPStan, PHP-CS-Fixer and Rector pass, and the changed files are valid PHP 8.2.

Requirements

• Documentation updates
  • Reference
  • Cookbooks
  • Changelog
• Unit tests

Breaking changes

The input \stdClass items lacking the property are now modified, as documented: code relying on the input staying untouched sees the mutation. The output content is the same.

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