code: public static HdfsHelper createHelper() {
          Configuration configuration = _lastKnownConfiguration;
          if (configuration == null) {
              try {
                  final SparkHadoopUtil sparkHadoopUtil = SparkHadoopUtil.get();
                  if (sparkHadoopUtil.isYarnMode()) {
                      configuration = sparkHadoopUtil.conf();
                  }
              } catch (final Exception e) {
                  // the above is developer API so we don't consider it very
                  // stable.
              }
          }
          return new HdfsHelper(configuration);
      }
docs: Creates a {@link HdfsHelper} without any configuration or context
  available. This is normally not the recommended way to obtain a
  {@link HdfsHelper} but may be necessary in executor functions where the
  {@link JavaSparkContext} is not in scope and not made available by Spark
  (at least spark's end-user API).
  
  @return