FIX

src/main/java/fr/eni/demo/bll/StockServiceImpl.java

@@ -43,7 +43,7 @@ public class StockServiceImpl implements StockService{
 
   @Override
   public Stock findByRef(String ref) {
-    Stock stock = stockRepository.findByRefEQ(ref);
+    Stock stock = stockRepository.findByRef(ref);
     if (stock == null) {
       throw new EntityNotFoundException("Ref non valide");
     }

src/main/java/fr/eni/demo/dal/StockRepository.java

@@ -9,5 +9,5 @@ import java.util.List;
 @Repository
 public interface StockRepository extends MongoRepository<Stock,Long> {
   List<Stock> findByNameIsContainingIgnoreCaseAndIsRentFalse(String name);
-  Stock findByRefEQ(String ref);
+  Stock findByRef(String ref);
 }