code: public Observable<WebhookInner> updateAsync(String resourceGroupName, String automationAccountName, String webhookName, WebhookUpdateParameters parameters) {
          return updateWithServiceResponseAsync(resourceGroupName, automationAccountName, webhookName, parameters).map(new Func1<ServiceResponse<WebhookInner>, WebhookInner>() {
              @Override
              public WebhookInner call(ServiceResponse<WebhookInner> response) {
                  return response.body();
              }
          });
      }
docs: Update the webhook identified by webhook name.
  
  @param resourceGroupName Name of an Azure Resource group.
  @param automationAccountName The name of the automation account.
  @param webhookName The webhook name.
  @param parameters The update parameters for webhook.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the WebhookInner object