Fix unmodifiable collection issue

Author: IvanBorislavovDimitrov

multiapps-controller-persistence/src/main/java/org/cloudfoundry/multiapps/controller/persistence/services/GcpObjectStoreFileStorage.java

@@ -14,7 +14,6 @@
 import java.util.Set;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
-
 import com.google.api.gax.retrying.RetrySettings;
 import com.google.auth.Credentials;
 import com.google.auth.oauth2.GoogleCredentials;
@@ -205,7 +204,7 @@ private int removeBlobsByFilter(Predicate<? super Blob> filter) {
                                                     .toList();
         List<Boolean> deletedBlobsResults = new ArrayList<>();
         if (!blobIds.isEmpty()) {
-            deletedBlobsResults = deleteBlobs(blobIds);
+            deletedBlobsResults.addAll(deleteBlobs(blobIds));
         }
 
         deletedBlobsResults.removeIf(Boolean.FALSE::equals);

multiapps-controller-persistence/src/test/java/org/cloudfoundry/multiapps/controller/persistence/services/GcpObjectStoreFileStorageTest.java

@@ -7,17 +7,16 @@
 import java.util.List;
 import java.util.Map;
 import java.util.UUID;
-
 import com.google.cloud.storage.Blob;
 import com.google.cloud.storage.BlobId;
 import com.google.cloud.storage.BlobInfo;
 import com.google.cloud.storage.Storage;
 import com.google.cloud.storage.contrib.nio.testing.LocalStorageHelper;
+import org.apache.commons.collections4.list.UnmodifiableList;
 import org.cloudfoundry.multiapps.controller.persistence.model.FileEntry;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.springframework.http.MediaType;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNull;
 
@@ -43,7 +42,7 @@ protected List<Boolean> deleteBlobs(List<BlobId> blobIds) {
                 for (BlobId blobId : blobIds) {
                     deletedBlobsResults.add(storage.delete(blobId));
                 }
-                return deletedBlobsResults;
+                return new UnmodifiableList<>(deletedBlobsResults);
             }
         };
         spaceId = UUID.randomUUID()