[Test] Fix IndicesClientDocumentationIT (#27899)

The last operation executed in IndicesClientDocumentationIT.testCreate()
 is an asynchronous index creation. Because nothing waits for its
 completion, on slow machines the index can sometimes be created after
 the testCreate() test is finished, and it can fail the following test.

 Closes #27754

Author: tlrx

client/rest-high-level/src/test/java/org/elasticsearch/client/documentation/IndicesClientDocumentationIT.java

@@ -61,50 +61,33 @@ public void testDeleteIndex() throws IOException {
             DeleteIndexRequest request = new DeleteIndexRequest("posts"); // <1>
             // end::delete-index-request
 
-            // tag::delete-index-execute
-            DeleteIndexResponse deleteIndexResponse = client.indices().deleteIndex(request);
-            // end::delete-index-execute
-            assertTrue(deleteIndexResponse.isAcknowledged());
-
-            // tag::delete-index-response
-            boolean acknowledged = deleteIndexResponse.isAcknowledged(); // <1>
-            // end::delete-index-response
-
-            // tag::delete-index-execute-async
-            client.indices().deleteIndexAsync(request, new ActionListener<DeleteIndexResponse>() {
-                @Override
-                public void onResponse(DeleteIndexResponse deleteIndexResponse) {
-                    // <1>
-                }
-
-                @Override
-                public void onFailure(Exception e) {
-                    // <2>
-                }
-            });
-            // end::delete-index-execute-async
-        }
-
-        {
-            DeleteIndexRequest request = new DeleteIndexRequest("posts");
             // tag::delete-index-request-timeout
             request.timeout(TimeValue.timeValueMinutes(2)); // <1>
             request.timeout("2m"); // <2>
             // end::delete-index-request-timeout
             // tag::delete-index-request-masterTimeout
             request.masterNodeTimeout(TimeValue.timeValueMinutes(1)); // <1>
-            request.timeout("1m"); // <2>
+            request.masterNodeTimeout("1m"); // <2>
             // end::delete-index-request-masterTimeout
             // tag::delete-index-request-indicesOptions
             request.indicesOptions(IndicesOptions.lenientExpandOpen()); // <1>
             // end::delete-index-request-indicesOptions
+
+            // tag::delete-index-execute
+            DeleteIndexResponse deleteIndexResponse = client.indices().deleteIndex(request);
+            // end::delete-index-execute
+
+            // tag::delete-index-response
+            boolean acknowledged = deleteIndexResponse.isAcknowledged(); // <1>
+            // end::delete-index-response
+            assertTrue(acknowledged);
         }
 
         {
             // tag::delete-index-notfound
             try {
                 DeleteIndexRequest request = new DeleteIndexRequest("does_not_exist");
-                DeleteIndexResponse deleteIndexResponse = client.indices().deleteIndex(request);
+                client.indices().deleteIndex(request);
             } catch (ElasticsearchException exception) {
                 if (exception.status() == RestStatus.NOT_FOUND) {
                     // <1>
@@ -113,4 +96,37 @@ public void onFailure(Exception e) {
             // end::delete-index-notfound
         }
     }
+
+    public void testDeleteIndexAsync() throws Exception {
+        final RestHighLevelClient client = highLevelClient();
+
+        {
+            Response createIndexResponse = client().performRequest("PUT", "/posts");
+            assertEquals(200, createIndexResponse.getStatusLine().getStatusCode());
+        }
+
+        {
+            DeleteIndexRequest request = new DeleteIndexRequest("posts");
+
+            // tag::delete-index-execute-async
+            client.indices().deleteIndexAsync(request, new ActionListener<DeleteIndexResponse>() {
+                @Override
+                public void onResponse(DeleteIndexResponse deleteIndexResponse) {
+                    // <1>
+                }
+
+                @Override
+                public void onFailure(Exception e) {
+                    // <2>
+                }
+            });
+            // end::delete-index-execute-async
+
+            assertBusy(() -> {
+                // TODO Use Indices Exist API instead once it exists
+                Response response = client.getLowLevelClient().performRequest("HEAD", "posts");
+                assertTrue(RestStatus.NOT_FOUND.getStatus() == response.getStatusLine().getStatusCode());
+            });
+        }
+    }
 }