code: public Observable<Void> beginRefreshHubSchemaAsync(String resourceGroupName, String serverName, String databaseName, String syncGroupName) {
          return beginRefreshHubSchemaWithServiceResponseAsync(resourceGroupName, serverName, databaseName, syncGroupName).map(new Func1<ServiceResponse<Void>, Void>() {
              @Override
              public Void call(ServiceResponse<Void> response) {
                  return response.body();
              }
          });
      }
docs: Refreshes a hub database schema.
  
  @param resourceGroupName The name of the resource group that contains the resource. You can obtain this value from the Azure Resource Manager API or the portal.
  @param serverName The name of the server.
  @param databaseName The name of the database on which the sync group is hosted.
  @param syncGroupName The name of the sync group.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceResponse} object if successful.