code: public Observable<RunbookInner> getAsync(String resourceGroupName, String automationAccountName, String runbookName) {
          return getWithServiceResponseAsync(resourceGroupName, automationAccountName, runbookName).map(new Func1<ServiceResponse<RunbookInner>, RunbookInner>() {
              @Override
              public RunbookInner call(ServiceResponse<RunbookInner> response) {
                  return response.body();
              }
          });
      }
docs: Retrieve the runbook identified by runbook name.
  
  @param resourceGroupName Name of an Azure Resource group.
  @param automationAccountName The name of the automation account.
  @param runbookName The runbook name.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the RunbookInner object