[Fix #1727] Adding MetaTransient annotation

Signed-off-by: Francisco Javier Tirado Sarti <ftirados@ibm.com>

Author: fjtirado

impl/persistence/api/src/main/java/io/serverlessworkflow/impl/persistence/metadata/MetaTransient.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.serverlessworkflow.impl.persistence.metadata;
+
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to mark an additional object POJO as transient, indicating that it should not be
+ * persisted.
+ */
+@Retention(RUNTIME)
+@Target(TYPE)
+public @interface MetaTransient {}

impl/persistence/api/src/main/java/io/serverlessworkflow/impl/persistence/metadata/PersistenceMetaUtils.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.serverlessworkflow.impl.persistence.metadata;
+
+import io.serverlessworkflow.impl.WorkflowInstanceData;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class PersistenceMetaUtils {
+
+  private PersistenceMetaUtils() {}
+
+  public static Stream<Entry<String, Object>> durableMetadataAsStream(
+      WorkflowInstanceData instance) {
+    return instance.metadata().entrySet().stream()
+        .filter(
+            e ->
+                e.getValue() != null
+                    && !e.getValue().getClass().isAnnotationPresent(MetaTransient.class));
+  }
+
+  public static Map<String, Object> durableMetadata(WorkflowInstanceData instance) {
+    return durableMetadataAsStream(instance)
+        .collect(Collectors.toMap(Entry::getKey, Entry::getValue));
+  }
+}

impl/persistence/bigmap/src/main/java/io/serverlessworkflow/impl/persistence/bigmap/BytesMapInstanceTransaction.java

@@ -39,6 +39,7 @@
 import io.serverlessworkflow.impl.persistence.hashing.HashItem;
 import io.serverlessworkflow.impl.persistence.hashing.HashMappingCoordinator;
 import io.serverlessworkflow.impl.persistence.hashing.HashMappingInfo;
+import io.serverlessworkflow.impl.persistence.metadata.PersistenceMetaUtils;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -130,7 +131,7 @@ protected byte[] marshallTaskCompleted(WorkflowContextData contextData, TaskCont
   }
 
   private void writeMetadata(WorkflowInstanceData instanceData, WorkflowOutputBuffer writer) {
-    Map<String, Object> additionalObjects = new HashMap<>(instanceData.metadata());
+    Map<String, Object> additionalObjects = PersistenceMetaUtils.durableMetadata(instanceData);
     writer.writeInt(additionalObjects.size());
     additionalObjects.forEach(
         (k, v) -> {

impl/persistence/tests/src/main/java/io/serverlessworkflow/impl/persistence/test/AbstractHandlerPersistenceTest.java

@@ -37,6 +37,7 @@
 import io.serverlessworkflow.impl.executors.TransitionInfo;
 import io.serverlessworkflow.impl.persistence.PersistenceInstanceHandlers;
 import io.serverlessworkflow.impl.persistence.WorkflowPersistenceInstance;
+import io.serverlessworkflow.impl.persistence.metadata.MetaTransient;
 import java.io.IOException;
 import java.time.Duration;
 import java.time.Instant;
@@ -52,6 +53,9 @@
 
 public abstract class AbstractHandlerPersistenceTest {
 
+  @MetaTransient
+  private record TransientMeta(String useless) {}
+
   private PersistenceInstanceHandlers handlers;
   private static WorkflowApplication app;
   private static WorkflowDefinition definition;
@@ -76,7 +80,8 @@ void setup() {
     when(workflowContext.context()).thenReturn(context);
     when(workflowContext.definition()).thenReturn(definition);
     when(workflowContext.instanceData()).thenReturn(workflowInstance);
-    when(workflowInstance.metadata()).thenReturn(Map.of("Javierito", "rules"));
+    when(workflowInstance.metadata())
+        .thenReturn(Map.of("Javierito", "rules", "ignored", new TransientMeta("ignored")));
     when(workflowInstance.startedAt()).thenReturn(beforeStart.plus(Duration.ofMillis(1)));
     when(workflowInstance.context()).thenReturn(context);
     when(workflowInstance.id()).thenReturn(app.idFactory().get());