Regenerate adexchangebuyer2 client (googleapis#4387)

This PR was generated using Autosynth. 🌈


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

```
2020-04-03 03:37:53,765 synthtool > Executing /tmpfs/src/git/autosynth/working_repo/synth.py.
2020-04-03 03:37:53,779 synthtool > Cloning https://github.com/googleapis/discovery-artifact-manager.git.
2020-04-03 03:37:54,394 synthtool > Cleaning output directory.
2020-04-03 03:37:54,396 synthtool > Installing dependencies.
2020-04-03 03:37:56,188 synthtool > Generating adexchangebuyer2 v2beta1.
2020-04-03 03:37:56,189 synthtool > 	1.30.1
WARNING:root:object without properties CancelNegotiationRequest: OrderedDict([(u'description', u'Request to cancel an ongoing negotiation.'), (u'type', u'object'), (u'properties', OrderedDict()), (u'id', u'CancelNegotiationRequest')])
WARNING:root:object without properties CompleteSetupRequest: OrderedDict([(u'properties', OrderedDict()), (u'id', u'CompleteSetupRequest'), (u'description', u"Request message for indicating that the proposal's setup step is complete."), (u'type', u'object')])
WARNING:root:object without properties Empty: OrderedDict([(u'properties', OrderedDict()), (u'id', u'Empty'), (u'description', u'A generic empty message that you can re-use to avoid defining duplicated\nempty messages in your APIs. A typical example is to use it as the request\nor the response type of an API method. For instance:\n\n    service Foo {\n      rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty);\n    }\n\nThe JSON representation for `Empty` is empty JSON object `{}`.'), (u'type', u'object')])
WARNING:root:object without properties ResumeProposalRequest: OrderedDict([(u'description', u'Request message to resume (unpause) serving for an already-finalized\nproposal.'), (u'type', u'object'), (u'properties', OrderedDict()), (u'id', u'ResumeProposalRequest')])
WARNING:root:object without properties StopWatchingCreativeRequest: OrderedDict([(u'id', u'StopWatchingCreativeRequest'), (u'description', u'A request for stopping notifications for changes to creative Status.'), (u'type', u'object'), (u'properties', OrderedDict())])
Writing json metadata to clients/google-api-services-adexchangebuyer2/v2beta1.metadata.json
2020-04-03 03:37:58,527 synthtool > Wrote metadata to clients/google-api-services-adexchangebuyer2/synth.metadata.

```
</details>

Author: yoshi-automation

clients/google-api-services-adexchangebuyer2/v2beta1.metadata.json

@@ -2,6 +2,6 @@
   "maven": {
     "groupId": "com.google.apis",
     "artifactId": "google-api-services-adexchangebuyer2",
-    "version": "v2beta1-rev20200215-1.30.9"
+    "version": "v2beta1-rev20200402-1.30.9"
   }
 }

clients/google-api-services-adexchangebuyer2/v2beta1/1.30.1/README.md

@@ -22,7 +22,7 @@ Add the following lines to your `pom.xml` file:
     <dependency>
       <groupId>com.google.apis</groupId>
       <artifactId>google-api-services-adexchangebuyer2</artifactId>
-      <version>v2beta1-rev20200215-1.30.9</version>
+      <version>v2beta1-rev20200402-1.30.9</version>
     </dependency>
   </dependencies>
 </project>
@@ -35,7 +35,7 @@ repositories {
   mavenCentral()
 }
 dependencies {
-  compile 'com.google.apis:google-api-services-adexchangebuyer2:v2beta1-rev20200215-1.30.9'
+  compile 'com.google.apis:google-api-services-adexchangebuyer2:v2beta1-rev20200402-1.30.9'
 }
 ```
 

clients/google-api-services-adexchangebuyer2/v2beta1/1.30.1/com/google/api/services/adexchangebuyer2/v2beta1/model/FilterSet.java

@@ -76,8 +76,16 @@ public final class FilterSet extends com.google.api.client.json.GenericJson {
   private java.lang.String environment;
 
   /**
-   * The list of formats on which to filter; may be empty. The filters represented by multiple
-   * formats are ORed together (i.e., if non-empty, results must match any one of the formats).
+   * Creative format bidded on or allowed to bid on, can be empty.
+   * The value may be {@code null}.
+   */
+  @com.google.api.client.util.Key
+  private java.lang.String format;
+
+  /**
+   * Creative formats bidded on or allowed to bid on, can be empty. Although this field is a list,
+   * it can only be populated with a single item. A HTTP 400 bad request error will be returned in
+   * the response if you specify multiple items.
    * The value may be {@code null}.
    */
   @com.google.api.client.util.Key
@@ -245,17 +253,36 @@ public FilterSet setEnvironment(java.lang.String environment) {
   }
 
   /**
-   * The list of formats on which to filter; may be empty. The filters represented by multiple
-   * formats are ORed together (i.e., if non-empty, results must match any one of the formats).
+   * Creative format bidded on or allowed to bid on, can be empty.
+   * @return value or {@code null} for none
+   */
+  public java.lang.String getFormat() {
+    return format;
+  }
+
+  /**
+   * Creative format bidded on or allowed to bid on, can be empty.
+   * @param format format or {@code null} for none
+   */
+  public FilterSet setFormat(java.lang.String format) {
+    this.format = format;
+    return this;
+  }
+
+  /**
+   * Creative formats bidded on or allowed to bid on, can be empty. Although this field is a list,
+   * it can only be populated with a single item. A HTTP 400 bad request error will be returned in
+   * the response if you specify multiple items.
    * @return value or {@code null} for none
    */
   public java.util.List<java.lang.String> getFormats() {
     return formats;
   }
 
   /**
-   * The list of formats on which to filter; may be empty. The filters represented by multiple
-   * formats are ORed together (i.e., if non-empty, results must match any one of the formats).
+   * Creative formats bidded on or allowed to bid on, can be empty. Although this field is a list,
+   * it can only be populated with a single item. A HTTP 400 bad request error will be returned in
+   * the response if you specify multiple items.
    * @param formats formats or {@code null} for none
    */
   public FilterSet setFormats(java.util.List<java.lang.String> formats) {

clients/google-api-services-adexchangebuyer2/v2beta1/1.30.1/pom.xml

@@ -8,8 +8,8 @@
 
   <groupId>com.google.apis</groupId>
   <artifactId>google-api-services-adexchangebuyer2</artifactId>
-  <version>v2beta1-rev20200215-1.30.9</version>
-  <name>Ad Exchange Buyer API II v2beta1-rev20200215-1.30.9</name>
+  <version>v2beta1-rev20200402-1.30.9</version>
+  <name>Ad Exchange Buyer API II v2beta1-rev20200402-1.30.9</name>
   <packaging>jar</packaging>
 
   <inceptionYear>2011</inceptionYear>