fix: restore room occupancy lost to case-sensitive xml attribute lookup

tests/Service/BookingSummaryAssemblerTest.php

@@ -70,6 +70,23 @@ class BookingSummaryAssemblerTest extends TestCase
         $this->assertSame(2, $summary->participantCount);
     }
 
+    public function testCreateStep1CountsRoomsWithUnknownOccupancyAsZero(): void
+    {
+        $service = $this->createService();
+        $bookingDto = $this->createBookingDto();
+        $bookingDto->travel->rooms[12] = $this->createRoom(12, null);
+        $bookingDto->currentStep = 1;
+        $bookingDto->roomSelections = [
+            $this->createRoomSelection(10, 1),
+            $this->createRoomSelection(12, 2),
+        ];
+
+        $summary = $service->getSummaryData($bookingDto);
+
+        // 1×2 for the known room; the room without occupancy contributes nothing.
+        $this->assertSame(2, $summary->participantCount);
+    }
+
     private function createService(): BookingSummaryAssembler
     {
         $priceCalculator = $this->createStub(BookingPriceCalculator::class);
@@ -107,7 +124,7 @@ class BookingSummaryAssemblerTest extends TestCase
         return new BookingDto($travel, 157047);
     }
 
-    private function createRoom(int $id, int $maxPax): Room
+    private function createRoom(int $id, ?int $maxPax): Room
     {
         $room = new Room();
         $room->id = $id;