fix nullpointer

src/main/java/com/sasiedzi/event/domain/TransactionItemComparator.java

@@ -1,6 +1,7 @@
 package com.sasiedzi.event.domain;
 
 import java.util.Comparator;
+import java.util.Objects;
 
 public class TransactionItemComparator implements Comparator<TransactionItem> {
 
@@ -11,7 +12,7 @@ public class TransactionItemComparator implements Comparator<TransactionItem> {
         if (item1 == null && item2 == null) return 0;
         if (item1 == null) return -1;
         if (item2 == null) return 1;
-        if (item1.getId().equals(item2.getId())) return 0;
+        if (Objects.equals(item1.getId(), item2.getId())) return 0;
 
         // Teraz porównujemy pola userAccount
         return compareUserAccounts(item1.getUserAccount(), item2.getUserAccount());

src/main/java/com/sasiedzi/event/domain/UserAccountComparator.java

@@ -4,6 +4,7 @@ import com.sasiedzi.event.service.Account;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Comparator;
+import java.util.Objects;
 
 public class UserAccountComparator implements Comparator<UserAccount> {
 
@@ -22,7 +23,7 @@ public class UserAccountComparator implements Comparator<UserAccount> {
         if (ua1 == null && ua2 == null) return 0;
         if (ua1 == null) return -1;
         if (ua2 == null) return 1;
-        if (ua1.getId().equals(ua2.getId())) return 0;
+        if (Objects.equals(ua1.getId(), ua2.getId())) return 0;
 
         String name1 = ua1.getName();
         String name2 = ua2.getName();