optimize code

src/main/java/com/faf223/expensetrackerfaf/service/ExpenseService.java

@@ -10,9 +10,13 @@ import java.util.List;
 @Service
 public class ExpenseService {
 
-    @Autowired
     private ExpenseRepository expenseRepository;
 
+    @Autowired
+    public ExpenseService(ExpenseRepository expenseRepository) {
+        this.expenseRepository = expenseRepository;
+    }
+
     public List<Expense> getExpensesByUserId(String userUuid) {
         return expenseRepository.findByUserUserUuid(userUuid);
     }

src/main/java/com/faf223/expensetrackerfaf/service/IncomeService.java

@@ -9,9 +9,14 @@ import java.util.List;
 
 @Service
 public class IncomeService {
-    @Autowired
+
     private IncomeRepository incomeRepository;
 
+    @Autowired
+    public IncomeService(IncomeRepository incomeRepository) {
+        this.incomeRepository = incomeRepository;
+    }
+
     public List<Income> getIncomesByUserId(String userUuid) {
         return incomeRepository.findByUserUserUuid(userUuid);
     }

src/main/java/com/faf223/expensetrackerfaf/service/UserService.java

@@ -8,9 +8,13 @@ import org.springframework.stereotype.Service;
 @Service
 public class UserService {
 
-    @Autowired
     private UserRepository userRepository;
 
+    @Autowired
+    public UserService(UserRepository userRepository) {
+        this.userRepository = userRepository;
+    }
+
     public User getUserById(String userUuid) {
         return userRepository.findById(userUuid).orElse(null);
     }