[Backport 2.x] Remove Demo Classes, add No-Op Step

.codecov.yml

@@ -1,10 +1,6 @@
 codecov:
   require_ci_to_pass: true
 
-# ignore files in demo package
-ignore:
-  - "src/main/java/demo"
-
 coverage:
   precision: 2
   round: down

src/main/java/org/opensearch/flowframework/workflow/NoOpStep.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+package org.opensearch.flowframework.workflow;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * A workflow step that does nothing. May be used for synchronizing other actions.
+ */
+public class NoOpStep implements WorkflowStep {
+
+    /** The name of this step, used as a key in the template and the {@link WorkflowStepFactory} */
+    public static final String NAME = "noop";
+
+    @Override
+    public CompletableFuture<WorkflowData> execute(List<WorkflowData> data) throws IOException {
+        return CompletableFuture.completedFuture(WorkflowData.EMPTY);
+    }
+
+    @Override
+    public String getName() {
+        return NAME;
+    }
+}

src/main/java/org/opensearch/flowframework/workflow/WorkflowStepFactory.java

@@ -10,14 +10,12 @@
 
 import org.opensearch.client.Client;
 import org.opensearch.cluster.service.ClusterService;
+import org.opensearch.core.rest.RestStatus;
+import org.opensearch.flowframework.exception.FlowFrameworkException;
 import org.opensearch.ml.client.MachineLearningNodeClient;
 
 import java.util.HashMap;
-import java.util.List;
 import java.util.Map;
-import java.util.concurrent.CompletableFuture;
-
-import demo.DemoWorkflowStep;
 
 /**
  * Generates instances implementing {@link WorkflowStep}.
@@ -39,31 +37,13 @@ public WorkflowStepFactory(ClusterService clusterService, Client client, Machine
     }
 
     private void populateMap(ClusterService clusterService, Client client, MachineLearningNodeClient mlClient) {
+        stepMap.put(NoOpStep.NAME, new NoOpStep());
         stepMap.put(CreateIndexStep.NAME, new CreateIndexStep(clusterService, client));
         stepMap.put(CreateIngestPipelineStep.NAME, new CreateIngestPipelineStep(client));
         stepMap.put(RegisterModelStep.NAME, new RegisterModelStep(mlClient));
         stepMap.put(DeployModelStep.NAME, new DeployModelStep(mlClient));
         stepMap.put(CreateConnectorStep.NAME, new CreateConnectorStep(mlClient));
         stepMap.put(ModelGroupStep.NAME, new ModelGroupStep(mlClient));
-
-        // TODO: These are from the demo class as placeholders, remove when demos are deleted
-        stepMap.put("demo_delay_3", new DemoWorkflowStep(3000));
-        stepMap.put("demo_delay_5", new DemoWorkflowStep(5000));
-
-        // Use as a default until all the actual implementations are ready
-        stepMap.put("placeholder", new WorkflowStep() {
-            @Override
-            public CompletableFuture<WorkflowData> execute(List<WorkflowData> data) {
-                CompletableFuture<WorkflowData> future = new CompletableFuture<>();
-                future.complete(WorkflowData.EMPTY);
-                return future;
-            }
-
-            @Override
-            public String getName() {
-                return "placeholder";
-            }
-        });
     }
 
     /**
@@ -75,8 +55,6 @@ public WorkflowStep createStep(String type) {
         if (stepMap.containsKey(type)) {
             return stepMap.get(type);
         }
-        // TODO: replace this with a FlowFrameworkException
-        // https://github.com/opensearch-project/opensearch-ai-flow-framework/pull/43
-        return stepMap.get("placeholder");
+        throw new FlowFrameworkException("Workflow step type [" + type + "] is not implemented.", RestStatus.NOT_IMPLEMENTED);
     }
 }

src/test/java/org/opensearch/flowframework/model/TemplateTestJsonUtil.java

@@ -14,6 +14,7 @@
 import org.opensearch.core.xcontent.ToXContent;
 import org.opensearch.core.xcontent.ToXContentObject;
 import org.opensearch.core.xcontent.XContentParser;
+import org.opensearch.flowframework.workflow.NoOpStep;
 
 import java.io.IOException;
 import java.util.List;
@@ -27,7 +28,7 @@
 public class TemplateTestJsonUtil {
 
     public static String node(String id) {
-        return nodeWithType(id, "placeholder");
+        return nodeWithType(id, NoOpStep.NAME);
     }
 
     public static String nodeWithType(String id, String type) {

src/test/java/org/opensearch/flowframework/workflow/NoOpStepTests.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+package org.opensearch.flowframework.workflow;
+
+import org.opensearch.test.OpenSearchTestCase;
+
+import java.io.IOException;
+import java.util.Collections;
+import java.util.concurrent.CompletableFuture;
+
+public class NoOpStepTests extends OpenSearchTestCase {
+
+    public void testNoOpStep() throws IOException {
+        NoOpStep noopStep = new NoOpStep();
+        assertEquals(NoOpStep.NAME, noopStep.getName());
+        CompletableFuture<WorkflowData> future = noopStep.execute(Collections.emptyList());
+        assertTrue(future.isDone());
+        assertFalse(future.isCompletedExceptionally());
+    }
+}