[NEW]mgmt resources, sync implementation for TaskGroup

sdk/resourcemanager/azure-resourcemanager-resources/CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### Features Added
 
+- Supported `invoke` and `invoke(ctx)` in `TaskGroup`.
+
 ### Breaking Changes
 
 ### Bugs Fixed

sdk/resourcemanager/azure-resourcemanager-resources/src/main/java/com/azure/resourcemanager/resources/fluentcore/dag/DAGraph.java

@@ -26,8 +26,8 @@ public class DAGraph<DataT, NodeT extends DAGNode<DataT, NodeT>> extends Graph<D
      */
     private final NodeT rootNode;
     /**
-     * the immediate parent graphs of this graph. A parent graph is the one with it's root
-     * depends on this graph's root.
+     * the immediate parent graphs of this graph. A parent graph is the one with its root
+     * depending on this graph's root.
      */
     protected List<DAGraph<DataT, NodeT>> parentDAGs;
     /**

sdk/resourcemanager/azure-resourcemanager-resources/src/main/java/com/azure/resourcemanager/resources/fluentcore/dag/FailedDependencyTaskException.java

@@ -0,0 +1,10 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package com.azure.resourcemanager.resources.fluentcore.dag;
+
+/**
+ * An FailedDependencyTaskException is emitted when a task cannot be executed due to a faulted decedent task.
+ */
+final class FailedDependencyTaskException extends RuntimeException {
+}

sdk/resourcemanager/azure-resourcemanager-resources/src/main/java/com/azure/resourcemanager/resources/fluentcore/dag/IndexableTaskItem.java

@@ -280,11 +280,21 @@ public Mono<Indexable> invokeAsync(TaskGroup.InvocationContext context) {
             });
     }
 
+    @Override
+    public Indexable invoke(TaskGroup.InvocationContext context) {
+        taskResult = this.invokeTask(context);
+        return taskResult;
+    }
+
     @Override
     public Mono<Void> invokeAfterPostRunAsync(boolean isGroupFaulted) {
         return Mono.empty();
     }
 
+    @Override
+    public void invokeAfterPostRun(boolean isGroupFaulted) {
+    }
+
     /**
      * Invokes a task asynchronously.
      *
@@ -293,6 +303,18 @@ public Mono<Void> invokeAfterPostRunAsync(boolean isGroupFaulted) {
      */
     protected abstract Mono<Indexable> invokeTaskAsync(TaskGroup.InvocationContext context);
 
+    /**
+     * Invokes a task synchronously.
+     *
+     * @param context Context of the invocation.
+     * @return an Observable upon subscription emits {@link Indexable}.
+     */
+    protected Indexable invokeTask(TaskGroup.InvocationContext context) {
+        //TODO(xiaofei) remove this default implementation
+        // once synchronous operation is supported across the board
+        return this.invokeTaskAsync(context).block();
+    }
+
     /**
      * Get an instance of VoidIndexable.
      *