fix: call object mapper with the expected class on 4.3

src/State/Processor/ObjectMapperInputProcessor.php

@@ -15,6 +15,7 @@
 
 use ApiPlatform\Metadata\Operation;
 use ApiPlatform\State\ProcessorInterface;
+use ApiPlatform\State\Util\StateOptionsTrait;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\ObjectMapper\ObjectMapperInterface;
 
@@ -25,6 +26,8 @@
  */
 final class ObjectMapperInputProcessor implements ProcessorInterface
 {
+    use StateOptionsTrait;
+
     /**
      * @param ProcessorInterface<mixed,mixed>|null $decorated
      */
@@ -51,7 +54,8 @@ public function process(mixed $data, Operation $operation, array $uriVariables =
         }
 
         $request = $context['request'] ?? null;
-        $mapped = $this->objectMapper->map($data, $request?->attributes->get('mapped_data'));
+        $mapped = $this->objectMapper->map($data, $request?->attributes->get('mapped_data') ?? $this->getStateOptionsClass($operation, $operation->getClass()));
+        $request?->attributes->set('mapped_data', $mapped);
 
         return $this->decorated ? $this->decorated->process($mapped, $operation, $uriVariables, $context) : $mapped;
     }

tests/Fixtures/TestBundle/ApiResource/MappedResource.php

@@ -23,6 +23,7 @@
     stateOptions: new Options(entityClass: MappedEntity::class),
     normalizationContext: [ContextBuilder::HYDRA_CONTEXT_HAS_PREFIX => false],
 )]
+#[Map(target: UnexpectedMappingTarget::class)]
 #[Map(target: MappedEntity::class)]
 final class MappedResource
 {

tests/Fixtures/TestBundle/ApiResource/UnexpectedMappingTarget.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace ApiPlatform\Tests\Fixtures\TestBundle\ApiResource;
+
+class UnexpectedMappingTarget
+{
+
+}