code: public Observable<VariableInner> updateAsync(String resourceGroupName, String automationAccountName, String variableName, VariableUpdateParameters parameters) {
          return updateWithServiceResponseAsync(resourceGroupName, automationAccountName, variableName, parameters).map(new Func1<ServiceResponse<VariableInner>, VariableInner>() {
              @Override
              public VariableInner call(ServiceResponse<VariableInner> response) {
                  return response.body();
              }
          });
      }
docs: Update a variable.
  
  @param resourceGroupName Name of an Azure Resource group.
  @param automationAccountName The name of the automation account.
  @param variableName The variable name.
  @param parameters The parameters supplied to the update variable operation.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the VariableInner object