code: public Observable<List<UsageInner>> listByAutomationAccountAsync(String resourceGroupName, String automationAccountName) {
          return listByAutomationAccountWithServiceResponseAsync(resourceGroupName, automationAccountName).map(new Func1<ServiceResponse<List<UsageInner>>, List<UsageInner>>() {
              @Override
              public List<UsageInner> call(ServiceResponse<List<UsageInner>> response) {
                  return response.body();
              }
          });
      }
docs: Retrieve the usage for the account id.
  
  @param resourceGroupName Name of an Azure Resource group.
  @param automationAccountName The name of the automation account.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the List&lt;UsageInner&gt; object