fix abstraction for previous commits

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

@@ -41,7 +41,7 @@ public class ExpenseService implements ITransactionService {
         return expenseRepository.findById(id).orElse(null);
     }
 
-    public void deleteExpenseById(long id) {
+    public void deleteTransactionById(long id) {
         expenseRepository.deleteById(id);
     }
 }

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

@@ -10,5 +10,6 @@ public interface ITransactionService {
     List<? extends IMoneyTransaction> getTransactions();
     List<? extends IMoneyTransaction> getTransactionsByEmail(String email);
     IMoneyTransaction getTransactionById(long id);
+    void deleteTransactionById(long it);
 
 }

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

@@ -41,7 +41,7 @@ public class IncomeService implements ITransactionService {
         return incomeRepository.findById(id).orElse(null);
     }
 
-    public void deleteIncomeById(long id) {
+    public void deleteTransactionById(long id) {
         incomeRepository.deleteById(id);
     }
 }