Convert workflow abstract class to interface

Signed-off-by: Artur Ciocanu <ciocanu@adobe.com>

Author: Artur Ciocanu

examples/src/main/java/io/dapr/examples/unittesting/DaprWorkflowExampleTest.java

@@ -42,7 +42,7 @@ public class DaprWorkflowExampleTest {
   private static final String noTimeoutWorkflow = "DemoWorkflowNoTimeout";
   private static final String workflowDefaultId = "demo-workflow-123";
 
-  private class DemoWorkflow extends Workflow {
+  private class DemoWorkflow implements Workflow {
 
     @Override
     public WorkflowStub create() {

examples/src/main/java/io/dapr/examples/workflows/chain/DemoChainWorkflow.java

@@ -16,7 +16,7 @@
 import io.dapr.workflows.Workflow;
 import io.dapr.workflows.WorkflowStub;
 
-public class DemoChainWorkflow extends Workflow {
+public class DemoChainWorkflow implements Workflow {
   @Override
   public WorkflowStub create() {
     return ctx -> {

examples/src/main/java/io/dapr/examples/workflows/childworkflow/DemoChildWorkflow.java

@@ -16,7 +16,7 @@
 import io.dapr.workflows.Workflow;
 import io.dapr.workflows.WorkflowStub;
 
-public class DemoChildWorkflow extends Workflow {
+public class DemoChildWorkflow implements Workflow {
   @Override
   public WorkflowStub create() {
     return ctx -> {

examples/src/main/java/io/dapr/examples/workflows/childworkflow/DemoWorkflow.java

@@ -16,7 +16,7 @@
 import io.dapr.workflows.Workflow;
 import io.dapr.workflows.WorkflowStub;
 
-public class DemoWorkflow extends Workflow {
+public class DemoWorkflow implements Workflow {
   @Override
   public WorkflowStub create() {
     return ctx -> {

examples/src/main/java/io/dapr/examples/workflows/continueasnew/DemoContinueAsNewWorkflow.java

@@ -18,7 +18,7 @@
 
 import java.time.Duration;
 
-public class DemoContinueAsNewWorkflow extends Workflow {
+public class DemoContinueAsNewWorkflow implements Workflow {
   /*
   Compared with a CRON schedule, this periodic workflow example will never overlap.
   For example, a CRON schedule that executes a cleanup every hour will execute it at 1:00, 2:00, 3:00 etc.

examples/src/main/java/io/dapr/examples/workflows/externalevent/DemoExternalEventWorkflow.java

@@ -16,7 +16,7 @@
 import io.dapr.workflows.Workflow;
 import io.dapr.workflows.WorkflowStub;
 
-public class DemoExternalEventWorkflow extends Workflow {
+public class DemoExternalEventWorkflow implements Workflow {
   @Override
   public WorkflowStub create() {
     return ctx -> {

examples/src/main/java/io/dapr/examples/workflows/faninout/DemoFanInOutWorkflow.java

@@ -20,7 +20,7 @@
 import java.util.List;
 import java.util.stream.Collectors;
 
-public class DemoFanInOutWorkflow extends Workflow {
+public class DemoFanInOutWorkflow implements Workflow {
   @Override
   public WorkflowStub create() {
     return ctx -> {

sdk-workflows/src/main/java/io/dapr/workflows/Workflow.java

@@ -21,16 +21,13 @@
 /**
  * Common interface for workflow implementations.
  */
-public abstract class Workflow {
-  public Workflow() {
-  }
-
+public interface Workflow {
   /**
    * Executes the workflow logic.
    *
    * @return A WorkflowStub.
    */
-  public abstract WorkflowStub create();
+  WorkflowStub create();
 
   /**
    * Executes the workflow logic.
@@ -39,7 +36,7 @@ public Workflow() {
    *            getting information about the current
    *            workflow instance.
    */
-  public void run(WorkflowContext ctx) {
+  default void run(WorkflowContext ctx) {
     WorkflowStub stub = this.create();
 
     if (!this.isSagaEnabled()) {
@@ -68,7 +65,7 @@ public void run(WorkflowContext ctx) {
     }
   }
 
-  public boolean isSagaEnabled() {
+  default boolean isSagaEnabled() {
     return this.getSagaOption() != null;
   }
 
@@ -77,7 +74,7 @@ public boolean isSagaEnabled() {
    * 
    * @return saga configuration
    */
-  public SagaOption getSagaOption() {
+  default SagaOption getSagaOption() {
     // by default, saga is disabled
     return null;
   }

sdk-workflows/src/main/java/io/dapr/workflows/WorkflowActivityContext.java

@@ -1,3 +1,16 @@
+/*
+ * Copyright 2023 The Dapr 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.dapr.workflows;
 
 public interface WorkflowActivityContext {

sdk-workflows/src/test/java/io/dapr/workflows/WorkflowTest.java

@@ -162,7 +162,7 @@ public void testWorkflow_WithSaga_compensateFaile() {
     verify(sagaContext, times(1)).compensate();
   }
 
-  public static class WorkflowWithoutSaga extends Workflow {
+  public static class WorkflowWithoutSaga implements Workflow {
     private final WorkflowStub stub;
 
     public WorkflowWithoutSaga(WorkflowStub stub) {
@@ -175,7 +175,7 @@ public WorkflowStub create() {
     }
   }
 
-  public static class WorkflowWithSaga extends Workflow {
+  public static class WorkflowWithSaga implements Workflow {
     private final WorkflowStub stub;
 
     public WorkflowWithSaga(WorkflowStub stub) {