Regenerate recommendationengine client (googleapis#6915)

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2021-01-23 03:53:02,123 synthtool [DEBUG] > Executing /home/kbuilder/.cache/synthtool/google-api-java-client-services/synth.py.
On branch autosynth-recommendationengine
nothing to commit, working tree clean
2021-01-23 03:53:02,539 synthtool [DEBUG] > Cloning https://github.com/googleapis/discovery-artifact-manager.git.
DEBUG:synthtool:Cloning https://github.com/googleapis/discovery-artifact-manager.git.
2021-01-23 03:53:02,926 synthtool [DEBUG] > Cleaning output directory.
DEBUG:synthtool:Cleaning output directory.
2021-01-23 03:53:02,929 synthtool [DEBUG] > Installing dependencies.
DEBUG:synthtool:Installing dependencies.
2021-01-23 03:53:04,582 synthtool [INFO] > Generating recommendationengine v1beta1.
INFO:synthtool:Generating recommendationengine v1beta1.
2021-01-23 03:53:04,582 synthtool [INFO] > 	1.31.0
INFO:synthtool:	1.31.0
WARNING:root:object without properties GoogleCloudRecommendationengineV1alphaRejoinCatalogMetadata: OrderedDict([(u'id', u'GoogleCloudRecommendationengineV1alphaRejoinCatalogMetadata'), (u'description', u'Metadata for TriggerCatalogRejoin method.'), (u'type', u'object'), (u'properties', OrderedDict())])
WARNING:root:object without properties GoogleCloudRecommendationengineV1alphaTuningResponse: OrderedDict([(u'properties', OrderedDict()), (u'description', u'Response associated with a tune operation.'), (u'id', u'GoogleCloudRecommendationengineV1alphaTuningResponse'), (u'type', u'object')])
WARNING:root:object without properties GoogleCloudRecommendationengineV1beta1RejoinUserEventsMetadata: OrderedDict([(u'id', u'GoogleCloudRecommendationengineV1beta1RejoinUserEventsMetadata'), (u'type', u'object'), (u'properties', OrderedDict()), (u'description', u'Metadata for RejoinUserEvents method.')])
WARNING:root:object without properties GoogleProtobufEmpty: OrderedDict([(u'id', u'GoogleProtobufEmpty'), (u'description', u'A generic empty message that you can re-use to avoid defining duplicated empty messages in your APIs. A typical example is to use it as the request or the response type of an API method. For instance: service Foo { rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty); } The JSON representation for `Empty` is empty JSON object `{}`.'), (u'properties', OrderedDict()), (u'type', u'object')])
Writing json metadata to clients/google-api-services-recommendationengine/v1beta1.metadata.json
2021-01-23 03:53:05,630 synthtool [DEBUG] > Wrote metadata to clients/google-api-services-recommendationengine/synth.metadata.
DEBUG:synthtool:Wrote metadata to clients/google-api-services-recommendationengine/synth.metadata.

```
</details>

Full log will be available here:
https://source.cloud.google.com/results/invocations/86db490f-caa7-4690-93e9-a5eb46d5d5dd/targets

- [ ] To automatically regenerate this PR, check this box.

Author: yoshi-automation

clients/google-api-services-recommendationengine/v1beta1.metadata.json

@@ -2,6 +2,6 @@
   "maven": {
     "groupId": "com.google.apis",
     "artifactId": "google-api-services-recommendationengine",
-    "version": "v1beta1-rev20210108-1.31.0"
+    "version": "v1beta1-rev20210115-1.31.0"
   }
 }

clients/google-api-services-recommendationengine/v1beta1/1.31.0/README.md

@@ -1,6 +1,6 @@
 # Recommendations AI (Beta) Client Library for Java
 
-Note that we now highly recommend new customers to use Retail API that incorporates the GA version of the Recommendations AI funtionalities. To enable Retail API, please visit https://console.cloud.google.com/apis/library/retail.googleapis.com. This is Recommendations AI service enables customers to build end-to-end personalized recommendation systems without requiring a high level of expertise in machine learning, recommendation system, or Google Cloud.
+Note that we now highly recommend new customers to use Retail API, which incorporates the GA version of the Recommendations AI funtionalities. To enable Retail API, please visit https://console.cloud.google.com/apis/library/retail.googleapis.com. The Recommendations AI service enables customers to build end-to-end personalized recommendation systems without requiring a high level of expertise in machine learning, recommendation system, or Google Cloud.
 
 This page contains information about getting started with the Recommendations AI (Beta)
 using the Google API Client Library for Java. In addition, you may be interested
@@ -22,7 +22,7 @@ Add the following lines to your `pom.xml` file:
     <dependency>
       <groupId>com.google.apis</groupId>
       <artifactId>google-api-services-recommendationengine</artifactId>
-      <version>v1beta1-rev20210108-1.31.0</version>
+      <version>v1beta1-rev20210115-1.31.0</version>
     </dependency>
   </dependencies>
 </project>
@@ -35,7 +35,7 @@ repositories {
   mavenCentral()
 }
 dependencies {
-  compile 'com.google.apis:google-api-services-recommendationengine:v1beta1-rev20210108-1.31.0'
+  compile 'com.google.apis:google-api-services-recommendationengine:v1beta1-rev20210115-1.31.0'
 }
 ```
 

clients/google-api-services-recommendationengine/v1beta1/1.31.0/com/google/api/services/recommendationengine/v1beta1/RecommendationsAI.java

@@ -20,7 +20,7 @@
  * Service definition for RecommendationsAI (v1beta1).
  *
  * <p>
- * Note that we now highly recommend new customers to use Retail API that incorporates the GA version of the Recommendations AI funtionalities. To enable Retail API, please visit https://console.cloud.google.com/apis/library/retail.googleapis.com. This is Recommendations AI service enables customers to build end-to-end personalized recommendation systems without requiring a high level of expertise in machine learning, recommendation system, or Google Cloud.
+ * Note that we now highly recommend new customers to use Retail API, which incorporates the GA version of the Recommendations AI funtionalities. To enable Retail API, please visit https://console.cloud.google.com/apis/library/retail.googleapis.com. The Recommendations AI service enables customers to build end-to-end personalized recommendation systems without requiring a high level of expertise in machine learning, recommendation system, or Google Cloud.
  * </p>
  *
  * <p>

clients/google-api-services-recommendationengine/v1beta1/1.31.0/pom.xml

@@ -8,8 +8,8 @@
 
   <groupId>com.google.apis</groupId>
   <artifactId>google-api-services-recommendationengine</artifactId>
-  <version>v1beta1-rev20210108-1.31.0</version>
-  <name>Recommendations AI (Beta) v1beta1-rev20210108-1.31.0</name>
+  <version>v1beta1-rev20210115-1.31.0</version>
+  <name>Recommendations AI (Beta) v1beta1-rev20210115-1.31.0</name>
   <packaging>jar</packaging>
 
   <inceptionYear>2011</inceptionYear>