Fix nullable transformable properties handling

src/Reflection/Types/PropertyTypeFactory.php

@@ -88,7 +88,7 @@ public static function create(RuntimeReflectionProperty $property)
 
         return new TransformableType(
             $type,
-            $isScalar,
+            $isNullable,
         );
     }
 }

tests/Integration/ClassTransformerFromArrayTest.php

@@ -18,6 +18,7 @@
 use Tests\Integration\DTO\UserEmptyTypeDTO;
 use ClassTransformer\Exceptions\ClassNotFoundException;
 
+use Tests\Integration\DTO\UserNullableArrayDTO;
 use function count;
 
 /**
@@ -221,4 +222,28 @@ public function testEmptyTypeObject(): void
         self::assertEquals($data['email'], $userDTO->email);
         self::assertEquals($data['balance'], $userDTO->balance);
     }
+
+    public function testNullableTransformableProperty(): void
+    {
+        $data = [
+            'user' => null,
+        ];
+
+        $userNullableDTO = Hydrator::init()->create(UserNullableArrayDTO::class, $data);
+
+        self::assertInstanceOf(UserNullableArrayDTO::class, $userNullableDTO);
+        self::assertNull($userNullableDTO->user);
+    }
+
+    public function testNotNullableTransformableProperty(): void
+    {
+        $data = [
+            'user' => $this->getBaseArrayData(),
+        ];
+
+        $userNullableDTO = Hydrator::init()->create(UserNullableArrayDTO::class, $data);
+
+        self::assertInstanceOf(UserNullableArrayDTO::class, $userNullableDTO);
+        self::assertInstanceOf(UserDTO::class, $userNullableDTO->user);
+    }
 }

tests/Integration/DTO/UserNullableArrayDTO.php

@@ -0,0 +1,9 @@
+<?php
+declare(strict_types=1);
+
+namespace Tests\Integration\DTO;
+
+class UserNullableArrayDTO
+{
+    public ?UserDTO $user;
+}

tests/Units/DTO/TypesDto.php

@@ -16,5 +16,5 @@ class TypesDto
     public ?string $emptyString;
     public ?float $nullableFloat;
     public ?bool $nullableBool;
-
+    public ?UserDTO $nullableObject;
 }

tests/Units/ValueCastingTest.php

@@ -79,6 +79,10 @@ public function testCreateProperty(): void
         $value = $caster->castAttribute(null);
         $this->assertNull($value);
 
+        $caster = new ValueCasting(new RuntimeReflectionProperty(new \ReflectionProperty(TypesDto::class, 'nullableObject')));
+        $value = $caster->castAttribute(null);
+        $this->assertNull($value);
+
     }
 
     public function testCreateArrayProperty(): void