code: @BetaApi
    public final Operation updateRegionAutoscaler(
        String autoscaler, String region, Autoscaler autoscalerResource, List<String> fieldMask) {
  
      UpdateRegionAutoscalerHttpRequest request =
          UpdateRegionAutoscalerHttpRequest.newBuilder()
              .setAutoscaler(autoscaler)
              .setRegion(region)
              .setAutoscalerResource(autoscalerResource)
              .addAllFieldMask(fieldMask)
              .build();
      return updateRegionAutoscaler(request);
    }
docs: Updates an autoscaler in the specified project using the data included in the request.
  
  <p>Sample code:
  
  <pre><code>
  try (RegionAutoscalerClient regionAutoscalerClient = RegionAutoscalerClient.create()) {
  String autoscaler = "";
  ProjectRegionName region = ProjectRegionName.of("[PROJECT]", "[REGION]");
  Autoscaler autoscalerResource = Autoscaler.newBuilder().build();
  List&lt;String&gt; fieldMask = new ArrayList&lt;&gt;();
  Operation response = regionAutoscalerClient.updateRegionAutoscaler(autoscaler, region.toString(), autoscalerResource, fieldMask);
  }
  </code></pre>
  
  @param autoscaler Name of the autoscaler to update.
  @param region Name of the region scoping this request.
  @param autoscalerResource Represents an Autoscaler resource. Autoscalers allow you to
  automatically scale virtual machine instances in managed instance groups according to an
  autoscaling policy that you define. For more information, read Autoscaling Groups of
  Instances. (== resource_for beta.autoscalers ==) (== resource_for v1.autoscalers ==) (==
  resource_for beta.regionAutoscalers ==) (== resource_for v1.regionAutoscalers ==)
  @param fieldMask The fields that should be serialized (even if they have empty values). If the
  containing message object has a non-null fieldmask, then all the fields in the field mask
  (and only those fields in the field mask) will be serialized. If the containing object does
  not have a fieldmask, then only non-empty fields will be serialized.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails