code: public AzkabanFetchExecuteFlowStatus fetchFlowExecution(String execId) throws AzkabanClientException {
      AzkabanMultiCallables.FetchFlowExecCallable callable =
          AzkabanMultiCallables.FetchFlowExecCallable.builder()
              .client(this)
              .execId(execId)
              .build();
  
      return runWithRetry(callable, AzkabanFetchExecuteFlowStatus.class);
    }
docs: Given an execution id, fetches all the detailed information of that execution,
  including a list of all the job executions.
  
  @param execId execution id to be fetched.
  
  @return The status object which contains success status and all the detailed
  information of that execution.