Fix ImagePullSecret serialization

Change-Id: Ibef8dffdaad21352ad7bc8bbf1f9bb81706f7261
diff --git a/operator/src/main/java/com/google/gerrit/k8s/operator/cluster/GerritClusterSpec.java b/operator/src/main/java/com/google/gerrit/k8s/operator/cluster/GerritClusterSpec.java
index 3fb827e..c4465a4 100644
--- a/operator/src/main/java/com/google/gerrit/k8s/operator/cluster/GerritClusterSpec.java
+++ b/operator/src/main/java/com/google/gerrit/k8s/operator/cluster/GerritClusterSpec.java
@@ -17,14 +17,13 @@
 import io.fabric8.kubernetes.api.model.LocalObjectReference;
 import java.util.HashSet;
 import java.util.Set;
-import java.util.stream.Collectors;
 
 public class GerritClusterSpec {
 
   private StorageClassConfig storageClasses;
   private SharedStorage gitRepositoryStorage;
   private SharedStorage logsStorage;
-  private Set<String> imagePullSecrets = new HashSet<>();
+  private Set<LocalObjectReference> imagePullSecrets = new HashSet<>();
 
   public StorageClassConfig getStorageClasses() {
     return storageClasses;
@@ -51,12 +50,10 @@
   }
 
   public Set<LocalObjectReference> getImagePullSecrets() {
-    return this.imagePullSecrets.stream()
-        .map(sec -> new LocalObjectReference(sec))
-        .collect(Collectors.toSet());
+    return imagePullSecrets;
   }
 
-  public void setImagePullSecrets(Set<String> imagePullSecrets) {
+  public void setImagePullSecrets(Set<LocalObjectReference> imagePullSecrets) {
     this.imagePullSecrets = imagePullSecrets;
   }
 }