chore(samples): improved message if no result returned in search tuto…

…rials. (#537)

…als.

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:
- [ ] Make sure to open an issue as a [bug/issue](https://github.com/googleapis/java-retail/issues/new/choose) before writing your code!  That way we can discuss the change, evaluate designs, and agree on the general idea
- [ ] Ensure the tests and linter pass
- [ ] Code coverage does not decrease (if any source code was changed)
- [ ] Appropriate docs were updated (if necessary)

Fixes #<issue_number_goes_here> ☕️

If you write sample code, please follow the [samples format](
https://github.com/GoogleCloudPlatform/java-docs-samples/blob/main/SAMPLE_FORMAT.md).

retail/interactive-tutorials/src/main/java/search/SearchSimpleQuery.java

@@ -60,7 +60,11 @@ public static void searchResponse(String defaultSearchPlacementName) throws IOEx
     // safely clean up any remaining background resources.
     try (SearchServiceClient client = SearchServiceClient.create()) {
       SearchResponse searchResponse = client.search(searchRequest).getPage().getResponse();
-      System.out.println("Search response: " + searchResponse);
+      if (searchResponse.getTotalSize() == 0) {
+        System.out.println("The search operation returned no matching results.");
+      } else {
+        System.out.println("Search response: " + searchResponse);
+      }
     }
   }
 }

retail/interactive-tutorials/src/main/java/search/SearchWithBoostSpec.java

@@ -71,7 +71,11 @@ public static void searchResponse(String defaultSearchPlacementName) throws IOEx
     // safely clean up any remaining background resources.
     try (SearchServiceClient client = SearchServiceClient.create()) {
       SearchResponse searchResponse = client.search(searchRequest).getPage().getResponse();
-      System.out.println("Search response: " + searchResponse);
+      if (searchResponse.getTotalSize() == 0) {
+        System.out.println("The search operation returned no matching results.");
+      } else {
+        System.out.println("Search response: " + searchResponse);
+      }
     }
   }
 }

retail/interactive-tutorials/src/main/java/search/SearchWithFacetSpec.java

@@ -62,7 +62,11 @@ public static void searchResponse(String defaultSearchPlacementName) throws IOEx
     // safely clean up any remaining background resources.
     try (SearchServiceClient client = SearchServiceClient.create()) {
       SearchResponse searchResponse = client.search(searchRequest).getPage().getResponse();
-      System.out.println("Search response: " + searchResponse);
+      if (searchResponse.getTotalSize() == 0) {
+        System.out.println("The search operation returned no matching results.");
+      } else {
+        System.out.println("Search response: " + searchResponse);
+      }
     }
   }
 }

retail/interactive-tutorials/src/main/java/search/SearchWithFiltering.java

@@ -63,7 +63,11 @@ public static void searchResponse(String defaultSearchPlacementName) throws IOEx
     // safely clean up any remaining background resources.
     try (SearchServiceClient client = SearchServiceClient.create()) {
       SearchResponse searchResponse = client.search(searchRequest).getPage().getResponse();
-      System.out.println("Search response: " + searchResponse);
+      if (searchResponse.getTotalSize() == 0) {
+        System.out.println("The search operation returned no matching results.");
+      } else {
+        System.out.println("Search response: " + searchResponse);
+      }
     }
   }
 }

retail/interactive-tutorials/src/main/java/search/SearchWithOrdering.java

@@ -62,7 +62,11 @@ public static void searchResponse(String defaultSearchPlacementName) throws IOEx
     // safely clean up any remaining background resources.
     try (SearchServiceClient client = SearchServiceClient.create()) {
       SearchResponse searchResponse = client.search(searchRequest).getPage().getResponse();
-      System.out.println("Search response: " + searchResponse);
+      if (searchResponse.getTotalSize() == 0) {
+        System.out.println("The search operation returned no matching results.");
+      } else {
+        System.out.println("Search response: " + searchResponse);
+      }
     }
   }
 }

retail/interactive-tutorials/src/main/java/search/SearchWithPagination.java

@@ -65,7 +65,11 @@ public static void searchResponse(String defaultSearchPlacementName) throws IOEx
     // safely clean up any remaining background resources.
     try (SearchServiceClient client = SearchServiceClient.create()) {
       SearchResponse searchResponseFirstPage = client.search(searchRequest).getPage().getResponse();
-      System.out.println("Search response: " + searchResponseFirstPage);
+      if (searchResponseFirstPage.getTotalSize() == 0) {
+        System.out.println("The search operation returned no matching results.");
+      } else {
+        System.out.println("Search response: " + searchResponseFirstPage);
+      }
 
       // PASTE CALL WITH NEXT PAGE TOKEN HERE:
 

retail/interactive-tutorials/src/main/java/search/SearchWithQueryExpansionSpec.java

@@ -68,7 +68,11 @@ public static void searchResponse(String defaultSearchPlacementName) throws IOEx
     // safely clean up any remaining background resources.
     try (SearchServiceClient client = SearchServiceClient.create()) {
       SearchResponse searchResponse = client.search(searchRequest).getPage().getResponse();
-      System.out.println("Search response: " + searchResponse);
+      if (searchResponse.getTotalSize() == 0) {
+        System.out.println("The search operation returned no matching results.");
+      } else {
+        System.out.println("Search response: " + searchResponse);
+      }
     }
   }
 }