Copy RealmId when passing it to TaskExecutorImpl (#879)

Realm id is a request-scoped component, so we need to copy it to ensure it is available when
the task is executed, even if the original realm id is no longer available because the
request has completed.

Author: adutra

polaris-core/src/main/java/org/apache/polaris/core/context/RealmId.java

@@ -37,6 +37,10 @@ static RealmId newRealmId(String id) {
     return ImmutableRealmId.of(id);
   }
 
+  static RealmId copyOf(RealmId realmId) {
+    return ImmutableRealmId.copyOf(realmId);
+  }
+
   @Value.Parameter
   @JsonValue
   String id();

service/common/src/main/java/org/apache/polaris/service/task/TaskExecutorImpl.java

@@ -97,7 +97,10 @@ public void addTaskHandler(TaskHandler taskHandler) {
    */
   @Override
   public void addTaskHandlerContext(long taskEntityId, RealmId realmId) {
-    tryHandleTask(taskEntityId, realmId, null, 1);
+    // Realm id is a request-scoped component, so we need to copy it to ensure it is available when
+    // the task is executed, even if the original realm id is no longer available because the
+    // request has completed.
+    tryHandleTask(taskEntityId, RealmId.copyOf(realmId), null, 1);
   }
 
   private @Nonnull CompletableFuture<Void> tryHandleTask(